What Is Citation Searching?

Citation searching (also called citation chasing or snowballing) finds relevant papers by following citation links: backward searching checks the reference list of a paper, and forward searching finds newer papers that cite it. It complements database searches, especially when terminology varies.

Types

• Backward citation searching: read the reference list of key papers and reviews to find earlier relevant work.
• Forward citation searching: use a tool that records citing articles (for example the "Cited by" link in Google Scholar, or citation indexes in commercial databases) to find later work.
• Related-article features: PubMed's "similar articles" suggest papers by content similarity, which is not the same as citation links.

How to do it

1. Choose seed papers: key studies you know are relevant.
2. Export the reference lists (backward) and citing papers (forward).
3. Screen new records for relevance and eligibility.
4. Repeat with newly found relevant papers until no new ones appear, or stop at a pre-defined round.
5. Record the tools, date and seed papers.

When it helps

• Fields with inconsistent vocabulary.
• Systematic reviews: citation searching is a recommended supplementary method.
• Finding the latest developments after a landmark paper.

Illustrative example

Invented for teaching. A review team identifies 12 included trials. Backward searching of those trials' references yields two additional trials; forward searching yields one more recent trial. The team reports the seed papers, tools and dates under "other methods" in the PRISMA flow diagram.

Limits and cautions

Citation searching is not a replacement for a database search, and citation tools differ in coverage. Newer papers have had less time to be cited, so forward searching favours older work. Be careful about self-citation, which can lead you to a narrow group of related papers. Finally, keep your screening criteria consistent: new records found by citation chasing should be judged against the same eligibility criteria as database records.

Common pitfalls

• Relying on only one citation tool, since coverage differs.
• Not recording seed papers and dates.

Key takeaways

• Chase citations in both directions.
• Document the process like any other search.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.