Citation index
A database that records which publications cite which, allowing you to trace a literature forwards in time.
Web of Science, Scopus, and Google Scholar are citation indexes: they store the citation links, not just the records. That is what makes “cited by” possible, and it is the most efficient way to move from a key older paper to the current state of a question.
Searching forwards from a landmark paper is often more productive than keyword searching, because it follows the field's own judgement about what mattered. Searching backwards through its reference list finds the foundations.
Do it on CitationEasy
See also
Citation countHow many later publications cite a given work, according to whichever index you ask.Research databaseA searchable collection of scholarly content, usually licensed by a library, covering a discipline or a publisher's catalogue.Impact factorA journal-level metric: the average number of citations in one year to articles the journal published in the two preceding years.