Primary vs Secondary Sources: How to Tell Them Apart
A primary source is the raw material you analyze. A secondary source is another scholar’s analysis of that material. The Harvard Guide to Using Sources treats that line as discipline-specific, the Library of Congress treats it as question-specific, and Primary Sources at Yale treats it as use-specific. This page is the what kind of source is this for my paper? decision across history, literature, the sciences, and the social sciences. It is not how to find historical primary sources and not scholarly vs popular.
By CitationEasy Editorial Team23 min read
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Quick Answer: Primary vs Secondary Sources
Ask what the source is doing in your paper, not how old it is or whether it looks official. If you are analyzing the source itself — a letter, a dataset, a poem, an original experiment — it is primary. If you are using someone else’s interpretation of that material, it is secondary. If you are using a digest of other people’s interpretations, it is tertiary.
A working sort
- Name the question. "How did newspapers describe the 1918 influenza?" and "What do historians now argue caused the 1918 influenza?" sort the same clipping two different ways.
- Primary. First-hand evidence for that question: a participant’s or witness’s record, an original creative work, raw data, or an empirical article that reports new results.
- Secondary. A later analysis, synthesis, or argument about those materials — a monograph, a review article, a textbook chapter, a historian’s interpretation.
- Tertiary. A compilation of primary and secondary work used for orientation: an encyclopedia, a handbook, most Wikipedia articles.
- When stuck. Change the question by one clause. If the category flips, the source was never "inherently" one type.
Publication type is a different axis. A peer-reviewed review article is still secondary. A daily newspaper can be primary for how an event was reported and secondary for the event itself. For the scholarly / popular / trade sort, use Scholarly vs popular sources.
Official Definitions You Can Trust
The shortest classroom definition is the one the Library of Congress puts on its Teachers’ Getting Started page and reprints, attributed to that Teacher’s Page, in the student research guide:
Library of Congress Teacher’s Page, as quoted in the student research guide
Primary sources are the raw materials of history — original documents and objects which were created at the time under study. They are different from secondary sources, accounts that retell, analyze, or interpret events, usually at a distance of time or place.
The Library’s Ask a Librarian FAQ (last updated 17 August 2020) restates the same idea for any discipline and names four official pairs so the test is not abstract:
Library of Congress, Ask a Librarian
A primary source is a first-hand record of an event or topic created by a participant in or a witness to that event or topic.
A secondary source is second-hand information written or created after an event. Secondary sources may summarize, interpret, review, or criticize existing events or works.
LOC’s official pairs:
An original painting by Mary Cassatt / a book about the artist Mary Cassatt. President Lincoln’s Gettysburg Address / an article about Abraham Lincoln. A photograph of Harry Houdini / a website about Houdini’s magic tricks. An original Gershwin musical score / a recent recording of Gershwin songs.
That wording is built for history classrooms and first-year papers. College work across departments needs the Harvard version, because a poem, a census table, and a chemistry paper are all primary in their own fields. The Harvard Guide to Using Sources opens with the assignment-and-discipline rule:
Harvard Guide to Using Sources, “Why Use Sources?”
What constitutes a useful and reliable source will vary according to both your assignment and the methods used in a particular field of study. As you approach a paper in an unfamiliar field, it will be important to remember that within each field of study, scholars distinguish between primary sources, or the raw material that they analyze as they attempt to answer a question, and secondary sources, or the analyses of that raw material done by other scholars in the field.
Primary Sources at Yale uses a one-sentence test that works in any department. The current FAQ (opened for this rewrite) is careful about later first-hand accounts and about artwork created after the fact:
Primary Sources at Yale, FAQ
Primary sources provide firsthand testimony or direct evidence concerning a topic or question under investigation.
They are usually created by witnesses or recorders who experienced the events or conditions being documented. Often these sources are created at the time when the events or conditions are occurring, but primary sources can also include artwork, autobiographies, memoirs, and oral histories recorded later.
Archivists use a still wider formula. The Guidelines for Primary Source Literacy, approved by ACRL in February 2018 and by the Society of American Archivists Council in June 2018, treat format as irrelevant:
Guidelines for Primary Source Literacy (ACRL/RBMS and SAA, 2018)
Primary sources are materials in a variety of formats that serve as original evidence documenting a time period, an event, a work, people, or ideas.
A tweet, a lab notebook, a quilt, a born-digital email, and a 1918 newspaper can all be primary. The question decides, not the file type. For the history-specific hunt — catalogs, Chronicling America, finding aids — use How to find historical primary sources.
The Same Source Can Be Primary or Secondary
This is the rule students miss, and it is not a blog tip. The University of Illinois History, Philosophy, and Newspaper Library states it in the primary-sources tutorial:
University of Illinois, History, Philosophy, and Newspaper Library
However, you should be aware that there's nothing inherent in a source that makes it primary or secondary. Instead, its category depends on how you treat it, which in turn depends on your research question.
Black Reconstruction in America, written in 1935 by W.E.B. Du Bois, could be used as a secondary source for research about 19th-century America, since Du Bois draws on a range of government reports, biographies, and existing historical narratives in order to make a claim about the past. However, it could also be used as a primary source for research about Du Bois’s life or black intellectual culture during the 1930s.
The book Illinois names is real: W. E. B. Du Bois, Black Reconstruction: An Essay Toward a History of the Part Which Black Folk Played in the Attempt to Reconstruct Democracy in America, 1860-1880 (New York: Harcourt, Brace, 1935). Illinois’s tutorial shortens the title to Black Reconstruction in America. For Reconstruction itself it is secondary. For 1930s historiography, or for Du Bois’s argument against the Dunning School, the same volume is primary.
Yale makes the same move with a journal rather than a book. On Types and Formats, serials are not a type; they are a use:
Primary Sources at Yale, “Types and Formats”
Like books, serials can function both as primary sources and secondary sources depending on how one approaches them.
For instance, an article on slavery in a recent issue of the Journal of Southern History should be read as a secondary source, as a scholar’s attempt to interpret primary source materials such as ledgers, diaries, or government documents in order to write an account of the past. An article on slavery published in the Journal of Southern History in 1935, however, can be read not only as a secondary source on slavery but also—and perhaps more appropriately—as a primary source that reveals how scholars in the 1930s interpreted slavery.
Yale is naming a real journal — the Journal of Southern History began with volume 1, number 1 (February 1935) — not inventing a specific article title. Do not invent one either. If you need a 1935 article, find it in the issue and cite that article.
Three quick flips
A newspaper:
A 12 September 2001 issue of The New York Times is primary for how U.S. papers reported the attacks the next morning. The same issue is secondary if you are using a reporter’s reconstruction of events you could document from court records, flight data, or official investigations.
A biography:
A life of Lincoln is secondary for Lincoln. It is primary if you are studying how a later decade portrayed him.
A review article:
A current literature review of mRNA vaccines is secondary for the vaccines. It is primary if you are studying what that field treated as settled in the year it was published.
What Counts as Primary in Each Discipline
Harvard’s guide is the official crosswalk. The examples below keep its wording and then name one real object in each field so the rule is not abstract.
Harvard Guide to Using Sources, field by field
Literature
For example, for literary scholars, primary sources include fiction and poetry, while secondary sources include criticism written by other scholars about those literary texts.
History
Historians, on the other hand, grapple with primary sources such as letters, diaries, and eyewitness accounts produced at the time of an event, as well as with secondary sources such as arguments presented by other historians.
Sociology
Sociologists tend to rely for raw material on quantitative data, such as surveys, censuses, and other statistics, or qualitative data, such as observation and interviews.
Psychology and economics
Social scientists in some fields, such as psychology and economics, also consider empirical journal articles (articles that describe the results of original research) published in peer-reviewed journals to be primary sources.
Anthropology and history articles
Social scientists in other fields, such as anthropology and history, however, do not consider research articles primary sources because articles in these fields do not typically present raw data.
Natural sciences
Natural scientists consider empirical articles published in peer-reviewed journals to be primary sources.
Science secondary sources
Secondary sources in the natural sciences include literature reviews and books.
| Field | Usually primary | Usually secondary |
|---|---|---|
| History | Letters, diaries, newspapers from the time, census schedules, oral histories | Later monographs and journal articles that interpret those records |
| Literature and arts | The novel, poem, play, score, or artwork itself | Criticism, biographies of the artist, reception studies |
| Natural sciences | Empirical articles that report new experiments or data | Literature reviews, methods books, textbooks |
| Psychology / economics | Empirical journal articles plus the underlying data | Reviews, handbooks, and books that synthesize those articles |
| Anthropology / history articles | Field notes, interviews, archival documents, datasets | The journal article that interprets those materials |
Cornell University Library compresses the same idea into one sentence you can take into any office hour. Its primary-sources tab also reprints Yale’s first-hand-testimony definition and a named photograph:
Cornell University, “What is a Source?”
Primary sources are the main text or work that you are discussing (e.g. a sonnet by William Shakespeare; an opera by Mozart); actual data or research results (e.g. a scientific article presenting original findings; statistics); or historical documents (e.g. letters, pamphlets, political tracts, manifestoes).
Copies, Digitization, and “Which One Is Real?”
Students often treat a PDF as a different kind of source from the letter it reproduces. Yale’s FAQ answers that directly. A copy can still do primary work if you are using it as evidence of the original statement. Cite the version you actually used, and say so when the assignment cares about the artifact.
Primary Sources at Yale, FAQ: copies of one letter
A single primary source may be found in a variety of formats. For example, the original of a handwritten letter by George Washington might be available to researchers at the Library of Congress, but a copy of that letter might be available elsewhere as microfilm, in a published collection of documents, or in electronic form online.
The same FAQ separates two digital words that get collapsed in bibliographies:
Primary Sources at Yale, FAQ: born-digital versus digitized
Born-digital materials start out in a digital form, like CDs or a website. Digitized materials are those that have been photographed or scanned to create a digital copy, like a PDF of a letter from an archive or a picture of a painting from a museum.
A scan of a 1918 newspaper is still primary for 1918 coverage. A 2024 museum website that explains that newspaper is secondary. A born-digital email from 2024 is primary for what that writer said that day. Yale’s Types and Formats page makes the same flip for dissertations:
Primary Sources at Yale, “Types and Formats”: dissertations
Although usually secondary sources, dissertations can themselves be primary sources or can be extremely helpful in identifying and locating primary sources.
Dissertations that function as primary sources might be edited versions of texts, or a doctoral thesis could be used to analyze the influence of a professor on a generation of graduate students and, by extension, on the teaching and writing in a discipline over a period of time.
Worked Examples (Real Sources Only)
History: Du Bois, 1935
Illinois already did the classification. Here is the bibliographic object so you can see what "the same book, two jobs" looks like on a works-cited page.
The source Illinois names
The book:
Du Bois, W. E. B. Black Reconstruction: An Essay Toward a History of the Part Which Black Folk Played in the Attempt to Reconstruct Democracy in America, 1860-1880. Harcourt, Brace, 1935.
Secondary for:
What happened during Reconstruction, and what government reports from the 1860s–1880s show. You are borrowing Du Bois’s interpretation.
Primary for:
How a Black intellectual in 1935 rewrote Reconstruction against the Dunning School. Now the 1935 argument is the evidence.
Sciences: Watson and Crick, 1953
Harvard’s science rule is concrete once you pick a real paper. J. D. Watson and F. H. C. Crick, "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid," Nature 171, no. 4356 (25 April 1953): 737–738, https://doi.org/10.1038/171737a0, is an empirical article. For a biology paper on DNA structure it is primary. Robert Olby’s The Path to the Double Helix (University of Washington Press, 1974; foreword by Francis Crick) is a historian’s reconstruction of that discovery — secondary for the structure, primary if you are studying 1970s history of molecular biology.
One paper, two later uses
Primary (the experiment / model):
Watson, J. D., and F. H. C. Crick. "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid." Nature 171, no. 4356 (25 April 1953): 737–738. https://doi.org/10.1038/171737a0.
Secondary (later interpretation):
Olby, Robert. The Path to the Double Helix. Seattle: University of Washington Press, 1974.
Tertiary (orientation only):
An encyclopedia or Wikipedia entry that summarizes the 1953 paper. Use it to find the DOI and the later histories; do not cite it as evidence of the structure.
Literature: Shakespeare’s sonnet, Mozart’s opera
Cornell’s official examples are the literary ones to keep: a sonnet by William Shakespeare and an opera by Mozart are primary because they are the works under discussion. A later critical book is secondary. If you need a named sonnet, use one Shakespeare actually wrote — Sonnet 18 ("Shall I compare thee to a summer’s day?") is in every standard edition — and cite the edition you held, not a memory of the first line.
Cornell’s literary pair, filled in
Primary:
The sonnet or the opera itself. Cornell’s wording: "a sonnet by William Shakespeare; an opera by Mozart."
Secondary:
Criticism of that work. The analysis is one step removed from the text.
Visual sources: Gardner’s Antietam photograph, 1862
Cornell’s primary-sources tab prints a named photograph so the visual case is not a generic "old picture." Alexander Gardner, Antietam, Md. President Lincoln with Gen. George B. McClellan and group of officers, 3 October 1862, Library of Congress. For a paper on how Lincoln presented himself after Antietam, the photograph is primary. A later essay that uses the image to argue about Civil War photography is secondary for Lincoln and primary only if your question is about that later essay.
Cornell’s named photograph
The item:
Gardner, Alexander, photographer. Antietam, Md. President Lincoln with Gen. George B. McClellan and group of officers. 3 October 1862. Library of Congress, https://www.loc.gov/item/2018666256/.
Primary for:
What that group looked like, how it was posed, and how a wartime photographer framed Lincoln on 3 October 1862.
Secondary if:
You treat a later caption or website write-up as your evidence of the battle itself. The photograph is not a substitute for after-action reports.
Maps: Illinois’s 1854 London cholera example
Illinois’s tutorial uses a map with two jobs at once: "this 1854 map provides evidence about the 1854 London cholera outbreak, but it also reflects a new understanding of how disease spreads and a concern with illness as a social problem." That is John Snow’s Broad Street investigation, the map historians actually mean when they say "the 1854 cholera map." Yale’s Types and Formats page adds the general rule: maps can be primary or secondary, because a map can also compile other maps and datasets.
One map, two questions
Primary for 1854:
Where cases clustered and how a contemporary investigator pictured the outbreak.
Primary for later history of science:
How mid-nineteenth-century observers argued that disease was a social and spatial problem.
Secondary if:
A modern textbook redraws Snow’s map to teach epidemiology. Cite the textbook for the lesson; cite a documented reproduction of Snow if the claim is about 1854.
Social sciences: a census and an interview
Harvard lists censuses and interviews as sociological raw material. The 1940 Census schedules at the National Archives are primary for who lived where and what they reported as their occupation in 1940. A 2020 journal article that models those schedules is secondary for 1940 labor — and primary if you are studying how twenty-first-century demographers reused the file.
An interview you conduct is primary data. A published oral history is also primary when you use the speaker’s words as testimony. It becomes secondary only when you are citing the interviewer’s framing rather than the speaker. The old shortcut "interviews by other people are secondary" is wrong.
Law and public speech: the text versus later commentary
Ask LOC’s Lincoln pair is the clean legal-and-rhetorical version of the same test. The Gettysburg Address is primary for what Lincoln said on 19 November 1863. An article about Abraham Lincoln is secondary for that speech. The same split holds for a court opinion: Brown v. Board of Education, 347 U.S. 483 (1954), is primary for what the Supreme Court held. A later textbook chapter that retells that holding is secondary. Do not cite a study guide as if it were the opinion.
Tertiary Sources: Useful Maps, Weak Citations
Cornell’s tertiary-sources page is the definition to keep. Encyclopedias and biographical dictionaries are the examples it names.
Cornell University Library
Tertiary sources are publications that summarize and digest the information in primary and secondary sources to provide background on a topic, idea, or event.
Encyclopedias and biographical dictionaries are good examples of tertiary sources.
Princeton’s Gender & Sexuality Studies guide (last updated 2 March 2026) puts the three layers in one chain: documents from the time of a revolution are primary; later historians produce secondary sources; an encyclopedia that summarizes those historians is tertiary. Illinois’s secondary-sources tutorial puts encyclopedias, bibliographies, and handbooks in that same leftover bin: useful, not the scholarship you are arguing with.
Wikipedia is the everyday case. It is a tertiary encyclopedia. Use it to harvest vocabulary and footnotes, then cite the published sources those footnotes point to. The workflow lives on How to use Wikipedia for academic research.
Textbooks sit on the line. Most current textbooks are secondary or tertiary: they synthesize a field for students. An older textbook can become primary if your question is how that field was taught in that year.
When a tertiary source is enough — and when it is not
- Use it to learn the standard name of a debate, to find a DOI, or to see which monograph everyone cites.
- Do not cite it as evidence that an event happened or that a study found a result. Quote the primary or secondary source the encyclopedia used.
- Cite it only if the assignment is about the reference work itself — for example, a paper on how Wikipedia frames a controversy.
When to Use Primary Sources vs Secondary Sources
Reach for primary sources when
- Your claim is about what a person, text, dataset, or experiment actually said or showed.
- You need evidence that is not already filtered through another scholar’s argument.
- The assignment asks for original analysis — close reading, archival work, or a methods result.
- You are writing in a field where the "raw material" is the work itself (a poem) or the empirical article.
Reach for secondary sources when
- You need the scholarly conversation: who has already argued what.
- You are writing a literature review or positioning a thesis against prior work.
- The primary record is unreadable without context — a legal formula, a 17th-century hand, a methods section outside your training.
- You need a map of which archives, datasets, or papers matter before you go find them.
Primary is not a grade. A diary can be self-serving. An empirical article can be retracted. A famous monograph can misread a document. The ACRL Framework treats authority as constructed and contextual: the source has to fit the claim. For the credibility decision, use How to tell if a source is credible. For the checklist, use How to evaluate sources.
How to Use Primary and Secondary Sources Together
Strong papers use both. Secondary sources tell you what is already argued and which primary items other people found. Primary sources let you test or extend that argument. A workable order:
- Start with a current secondary source or a literature review so you do not reinvent a settled debate.
- Write down the primary items those scholars actually cite — not just their conclusions.
- Get those items (or a documented digital surrogate) and read them against the claim.
- Keep the secondary source for historiography, methods, or a point you are qualifying.
- Cite each source for the job it did. Do not launder a primary quotation through a textbook if you held the original.
A worked research question
Question: How did World War II change women’s waged work in the United States? That question is still a good one. The sources have to be real.
Real items for that question
Primary — official poster:
J. Howard Miller, We Can Do It!, ca. 1942–1943, War Production Board, National Archives Identifier 535413. NARA’s still-pictures note records that Westinghouse commissioned the poster for internal use and that it later became associated with the public "Rosie the Riveter" image.
Primary — census:
Sixteenth Census of the United States, 1940. Occupation and industry tables, and the manuscript schedules at the National Archives.
Secondary — later history:
Alice Kessler-Harris, Out to Work: A History of Wage-Earning Women in the United States (New York: Oxford University Press, 1982; 20th anniversary ed., 2003). Use it for the long argument about wage work; do not treat it as 1940s testimony.
What this mix does:
The poster is evidence of wartime workplace messaging, not of how many women entered factories. The census is evidence of reported occupations. Kessler-Harris is evidence of how a labor historian later interpreted those changes. Each source answers a different clause of the question.
Illinois’s Three Questions Before You Trust a Primary Source
Primary sources are closer to the event or the work, not closer to the truth. Illinois’s tutorial asks three questions before you trust one. A propaganda poster and a census schedule are both primary. They are not interchangeable evidence.
University of Illinois primary-sources tutorial
When and where was it created?
Who created it?
For what purpose or audience was it produced?
Common Mistakes
Treating primary as automatically better
Primary sources carry the creator’s purpose, audience, and blind spots. Illinois’s 1959 Nixon-in-the-Soviet-Union clipping is primary for what that journalist and those editors thought readers would care about the next day. It is not a complete record of the visit. Ask the three questions above before you let one artifact settle the claim.
Using only secondary sources
If every footnote is a textbook or a review, you are reporting other people’s readings. Introductory courses sometimes want that. Upper-level and research assignments usually want you to touch the thing those people read. When the primary item is behind a paywall or in an archive, say so and use the best documented surrogate you can get — a library scan, a documentary edition, a dataset with a codebook.
Sorting by format or by .edu
A PDF is not a type. Yale’s Washington-letter example is the official warning: microfilm, a published collection, and an online scan can all be the same primary source in different containers. A university press book can be secondary (most monographs) or primary (a published diary, a 1935 argument you are studying as a 1935 argument). A government website can publish primary data and secondary commentary on the same page. Read the item, then classify the use.
Confusing scholarly with primary
Peer review answers "who checked this before publication?" Primary vs secondary answers "is this the raw material or the analysis?" A scholarly review article is secondary. A popular magazine interview can be primary for the interviewee’s public statement. Keep the two sorts on Scholarly vs popular sources and this page from collapsing into each other.
Ignoring tertiary sources instead of using them first
You should not cite Wikipedia as proof. You should use it — and subject encyclopedias — to learn the vocabulary and to collect better citations. Skipping the map is how students miss the standard book on a topic.
Treating a translation or a modern edition as the original
A facing-page translation is primary for what the translator wrote and secondary for the source-language wording unless you can check that wording. A modern spelling-modernized Shakespeare is still the play, but the edition you held is the one to cite. If the claim depends on a specific word, get as close to the original-language text as your assignment allows.
Where to Find More of Each Type
This page stops at classification. The finding work lives on sibling guides so the three URLs stay different jobs.
- Historical documents and digitized collections: How to find historical primary sources — Library of Congress, NARA, DPLA, Chronicling America.
- Unpublished boxes and finding aids: How to find and use archives.
- Articles, books, and reviews: How to find scholarly sources and Library databases.
- Grey reports that are not quite either: Grey literature.
Frequently Asked Questions
- Is Wikipedia a primary or secondary source?
- Usually neither. Cornell and most college libraries treat encyclopedias as tertiary sources: they summarize primary and secondary work. Wikipedia says the same thing about itself. Use the article to find sources; cite those sources. It becomes primary only if your paper is about Wikipedia — for example, how an article changed after a news event.
- Are textbooks primary or secondary sources?
- Most current textbooks are secondary or tertiary. They digest research for students. An older textbook can be primary if you are studying how a field was taught in that year — the same flip Illinois describes for Du Bois and Yale describes for a 1935 journal article.
- Is a peer-reviewed journal article a primary source?
- Only in some fields, and only some articles. Harvard: natural scientists, and some social scientists in psychology and economics, treat empirical articles that report original results as primary. Literature reviews and books are secondary. In history and anthropology, the journal article is usually secondary because it interprets data rather than presenting the data as the object of study.
- Are interviews I conduct primary sources?
- Yes. Interviews you run are primary data — Harvard lists interviews with surveys and censuses as sociological raw material. Published interviews and oral histories are also primary when you quote the speaker as a witness. They are not automatically secondary just because someone else recorded them.
- Can a newspaper article be both primary and secondary?
- Yes. Yale’s rule for serials is the clean version: a recent scholarly article about slavery is secondary for slavery; a 1935 article on the same subject can be primary for 1930s historiography. A newspaper from the day of an event is primary for coverage; it is secondary if you are using the reporter as your only account of facts better taken from records.
- Should I cite tertiary sources in a research paper?
- Almost never as evidence. Cite them if the assignment is about the reference work, or if your instructor explicitly allows a handbook definition. Otherwise, take the encyclopedia’s bibliography and cite the books and articles it used.
- How many primary versus secondary sources do I need?
- There is no official ratio. Follow the assignment and the field. A literature paper may rest on one primary text and several critical articles. A history paper usually needs both archival or contemporary documents and later scholarship. A lab report’s primary source is often your own data plus the empirical papers you replicate or extend.
- Can a blog post or social-media post be a primary source?
- Yes, if your question is about that public statement, that platform, or that moment — ACRL/SAA count original evidence in any format, and Yale lists social-media updates as digital ephemera. A CEO’s post is primary for what the company said that day. It is a weak secondary source for industry-wide statistics. Classify the use, then decide whether the source is credible for the claim.
- Is a digitized scan still a primary source?
- Yes, if you are using it as evidence of the original statement. Yale’s Washington-letter example is the official version: the handwritten letter at the Library of Congress, a microfilm copy, a published documentary edition, and an online scan can all be the same primary source in different formats. Cite the version you used. A modern website that only explains the letter is secondary.
- Is a dissertation a primary or secondary source?
- Usually secondary: Yale calls dissertations book-length studies based on original research. The same dissertation becomes primary if you are studying the advisor’s influence, a generation of graduate training, or the dissertation as a text. Its bibliography is also a map to the primary items the writer actually used.
Classify the source, then cite the thing you actually used
Once you know whether a source is doing primary, secondary, or tertiary work in the paper, format the item you held — the edition, the DOI, the archive identifier. The generator will not decide the category for you.