Citation chaining finds papers your keyword search missed by starting from a known seed paper and moving in two directions: forward through its cited-by links to newer studies that cite it, and backward through its reference list to earlier studies it builds on. Screen titles and abstracts at each step and note which direction surfaced relevant new work.
Run the chain in order
- Pick one seed paper that sits squarely on your topic. Confirm it is the right starting point by checking that its title and abstract match your research question; a loosely related seed sends both directions off target.
- Go backward first. Open the seed's reference list and screen each title and abstract against your inclusion criteria. Record the ones that qualify and mark them as backward results.
- Go forward next. Use the seed's cited-by link to list papers that cite it, then screen those titles and abstracts the same way. Record qualifying papers as forward results.
- Repeat on the strongest new papers. Treat each newly included paper as a new seed and run both directions again. Stop when a round produces no new relevant studies.
- Keep a short log. For each seed, note the direction that produced new relevant studies and the ones it did not, so you can describe your method and avoid re-checking the same links.
What each direction gives you
Backward chaining reaches the foundational and earlier work the seed cites, which is often missed when keyword terms have changed over time. Forward chaining reaches later studies that cite the seed, including work published after your keyword search was run. Cochrane's guidance on searching includes searching reference lists and other sources alongside database searches, and it stresses documenting searches and managing the records you retrieve.
Tools that expose the links
Google Scholar provides cited-by links and related-article links on its results, and it supports title searches in quotation marks plus date sorting. The Semantic Scholar Academic Graph API offers paper and citation endpoints, which lets you pull citation lists programmatically when a chain grows large.
Screen as you go
Apply the same title-and-abstract criteria at every step so forward and backward results are judged consistently. When a title is ambiguous, keep it for full-text review and record why. The direction log then shows whether your seed was better connected to earlier or later literature, which tells you where to spend remaining time before the deadline.