In searching for research articles, we often want to obtain lists of references from across studies, and also obtain lists of articles that cite a particular study. In systematic reviews, this supplementary search technique is known as ‘citation chasing’: forward citation chasing looks for all records citing one or more articles of known relevance; backward ciation chasing looks for all records referenced in one or more articles.

Traditionally, this process would be done manually, and the resulting records would need to be checked one-by-one against included studies in a review to identify potentially relevant records that should be included in a review.

This package contains functions to automate this process by making use of the API. An input article list can be used to return a list of all referenced records, and/or all citing records in the database (consisting of PubMed, PubMed Central, CrossRef, Microsoft Academic Graph and CORE; ‘’).

USERS MUST OBTAIN A TOKEN FOR THE LENS.ORG SCHOLARLY API (available for free here). The API may be time limited, but not rate limited. Requests for tokens may need initial approval from The Lens.

A shiny app version of the package is available here. This version requires no API and is immediately usable and free.

Install the package using the following code: devtools::install_github("nealhaddaway/citationchaser")

Please cite as:
Haddaway, N. R., Grainger, M. J., Gray, C. T. 2021. citationchaser: An R package and Shiny app for forward and backward citations chasing in academic searching. doi: 10.5281/zenodo.4543513
Citation in .ris format (right click ‘Save Link As’)


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