Grey Literature: What It Is and How to Find It

Grey literature encompasses research materials not published through traditional academic channels. Learn what constitutes grey literature, why it's valuable for research, where to find technical reports, dissertations, and government documents, and how to evaluate these alternative sources.

What Is Grey Literature?

Definition

Grey literature (or gray literature) refers to research and information produced by organizations outside traditional commercial or academic publishing. It's called "grey" because it exists in the space between white (published) literature and black (unpublished) materials.

The Luxembourg Convention defines grey literature as: "that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers."

Characteristics of Grey Literature

Types of Grey Literature

Government Documents and Reports

Research and information produced by government agencies:

• Technical reports and white papers
• Statistical reports and data
• Policy briefings and recommendations
• Congressional hearings and testimony
• Agency publications and guidelines
• Grant reports and program evaluations

Theses and Dissertations

Graduate student research submitted for degrees:

• Doctoral dissertations
• Master's theses
• Honor's theses (undergraduate)

Value: Often contain extensive literature reviews and original research, though quality varies by institution and field.

Conference Papers and Proceedings

Research presented at academic and professional conferences:

• Conference abstracts
• Poster presentations
• Slide decks and presentations
• Full conference proceedings

Technical Reports

Detailed research reports from various organizations:

• Corporate research reports
• NGO research and evaluations
• Think tank publications
• Research institute reports
• Laboratory reports

Working Papers and Preprints

Research in progress or before formal publication:

• Working papers from research institutions
• Preprints in subject repositories
• Discussion papers
• Research notes

Other Grey Literature Types

• Clinical trial data and protocols
• Patents and technical standards
• Annual reports from organizations
• Market research and industry reports
• Policy documents and white papers
• Newsletters and bulletins
• Fact sheets and briefing documents

Why Grey Literature Matters

Advantages of Grey Literature

When Grey Literature Is Essential

• Policy research: Government reports and policy analyses
• Current data: Recent statistics and reports
• Applied fields: Professional practice guidelines
• Emerging topics: Cutting-edge research before formal publication
• Local issues: Regional reports and community studies
• Systematic reviews: Comprehensive literature searches must include grey literature

Finding Grey Literature

General Grey Literature Databases

Dissertations and Theses

• ProQuest Dissertations and Theses Global: Largest database (library subscription)
• NDLTD (Networked Digital Library of Theses and Dissertations): Free access to international dissertations
• Institutional repositories: University digital libraries
• DART-Europe: European dissertations
• British Library EThOS: UK doctoral theses

Government Sources

United States

• USA.gov: Portal to government information
• GovInfo: Federal government publications
• CDC Publications: Health research and data
• NIH Reports: Medical and health research
• Congressional Research Service: Policy reports
• GAO Reports: Government Accountability Office studies

International

• World Bank Open Knowledge: Development research
• UN iLibrary: United Nations publications
• WHO Publications: World Health Organization reports
• OECD iLibrary: Economic and policy research
• European Commission: EU research and reports

Conference Papers

• IEEE Xplore: Engineering and computer science conferences
• ACM Digital Library: Computing conferences
• Conference Proceedings Citation Index (Web of Science): Multidisciplinary
• PapersFirst: Conference papers and proceedings
• Individual conference websites: Often post proceedings freely

Preprints and Working Papers

• arXiv: Physics, math, computer science preprints
• SSRN: Social science research network
• bioRxiv: Biology preprints
• medRxiv: Medical research preprints
• RePEc: Economics working papers
• PsyArXiv: Psychology preprints

Think Tanks and Research Institutes

Major think tanks publish extensive grey literature:

• Brookings Institution
• RAND Corporation
• Urban Institute
• Center for Strategic and International Studies
• Pew Research Center
• Check think tank websites directly for reports

Search Strategies for Grey Literature

Keyword Strategies

Use document type terms in your searches:

Google Searching Techniques

Google can be effective for finding grey literature:

• Use filetype: operator (e.g., filetype:pdf "climate change" report)
• Search site: specific domains (e.g., site:.gov or site:.org)
• Use Google Scholar for technical reports and theses
• Try Google Advanced Search with specific file formats

Organizational Searching

1. Identify key organizations in your field
2. Visit their websites directly
3. Look for "Publications," "Research," or "Resources" sections
4. Check for publication archives or databases
5. Sign up for newsletters to receive new publications

Citation Chasing

Find grey literature through references:

• Check reference lists in relevant articles
• Look for technical report citations
• Search for cited reports by title or organization
• Use "Cited by" in Google Scholar for grey literature

Evaluating Grey Literature

Quality Assessment Criteria

Grey literature requires careful evaluation since it lacks traditional peer review:

Evaluating Different Grey Literature Types

Government Reports

Generally reliable for factual information and data. Consider political context and agency mission. Check if reports were reviewed or contested.

Think Tank Publications

Variable quality. Check funding sources and institutional bias. Compare findings across think tanks with different perspectives.

Dissertations

Academically rigorous but committee-reviewed, not peer-reviewed. Quality varies by institution. Recent dissertations may contain cutting-edge research.

Preprints

Not peer-reviewed yet. May contain errors or unverified claims. Check if peer-reviewed version now exists. Use cautiously and verify key findings.

Conference Papers

Preliminary research. Often early-stage findings. Check if full study was later published. Some conferences have rigorous review; others don't.

Red Flags

• No author or organization identified
• Hidden or undisclosed funding sources
• Methodology not described
• No citations or data sources
• Obvious commercial or political agenda
• Findings that contradict established evidence without explanation

Using Grey Literature in Research

When to Use Grey Literature

• Supplement peer-reviewed research: Add current data and perspectives
• Fill gaps: Topics not covered in academic literature
• Provide context: Policy background and practical applications
• Access data: Original datasets and detailed methods
• Systematic reviews: Required for comprehensive literature searches

Balancing Grey and Published Literature

Best practices for incorporating grey literature:

1. Build foundation with peer-reviewed sources
2. Add grey literature for currency and breadth
3. Acknowledge grey literature status in your writing
4. Verify key facts in multiple sources
5. Be transparent about source types in citations

Citation Considerations

Citing grey literature properly:

• Include all available information (author, organization, date, title)
• Note report numbers or series information
• Provide URLs for online sources
• Include retrieval dates for unstable sources
• Check style guide for specific grey literature citation formats

Grey Literature by Discipline

Health and Medicine

Key sources: Clinical trial registries, WHO reports, CDC publications, pharmaceutical research, hospital protocols

Social Sciences

Key sources: Government statistics, policy briefs, think tank reports, NGO evaluations, community assessments

Sciences and Engineering

Key sources: Technical reports, conference papers, patents, industry standards, laboratory reports

Education

Key sources: Educational research reports, curriculum materials, program evaluations, policy documents, dissertations

Business and Economics

Key sources: Market research, industry reports, working papers, annual reports, economic forecasts

Challenges and Limitations

Access Issues

• Not indexed in standard databases
• May require direct contact with organizations
• Physical copies may be hard to obtain
• Copyright and permissions can be complex
• Links may break or content be removed

Quality Concerns

• Variable quality without peer review
• Potential bias from funders or sponsors
• May lack rigorous methodology
• Not always replicable or verifiable

Documentation Challenges

• Missing citation information
• No DOI or permanent identifier
• Difficult to retrieve later
• Version control issues (which version did you use?)

Best Practices for Grey Literature Research

Search Systematically

1. Use multiple search strategies and sources
2. Document your search process
3. Keep track of where you found items
4. Note any access restrictions
5. Save copies immediately (may disappear)

Evaluate Critically

1. Apply same evaluation criteria as any source
2. Be more cautious with non-peer-reviewed materials
3. Verify key facts in multiple sources
4. Consider author/organization expertise and bias
5. Check funding sources and conflicts of interest

Document Thoroughly

1. Record complete citation information immediately
2. Save PDFs or print copies
3. Note retrieval dates
4. Screenshot or archive web pages that might change
5. Keep notes on source evaluation

Frequently Asked Questions

Is grey literature acceptable for academic research?

Yes, when used appropriately. Grey literature is essential for comprehensive research, especially in applied fields, policy studies, and systematic reviews. However, it should typically supplement rather than replace peer-reviewed sources. Check with your instructor about expectations.

How do I know if grey literature is credible?

Evaluate authorship, organizational reputation, methodology, evidence quality, and transparency about funding and purpose. Government reports and dissertations are generally reliable. Industry-funded research requires careful scrutiny for bias.

Can I cite unpublished dissertations?

Yes. Dissertations are commonly cited in academic work. Include the university, degree type, and year. Note whether it's published in ProQuest or available only from the university library.

What's the difference between grey literature and preprints?

Preprints are a type of grey literature—specifically, research manuscripts shared before peer review. Other grey literature may never undergo peer review (like government reports or technical reports).

How do I find grey literature for systematic reviews?

Use specialized grey literature databases (OpenGrey, government sites), search preprint servers, check conference proceedings, contact experts for unpublished data, and search organizational websites. Document all search strategies thoroughly.

Related Guides

• Scholarly vs Popular Sources: What's the Difference?
• Open Access Research: Finding Free Academic Sources
• How to Tell If a Source is Credible: Complete Guide