In theory, authors cite an item because it is relevant to the topic of their own work. The original and best-known database for citation searching is Web of Science. Other databases have added this feature, but their citation coverage is weak for older articles.
Web of Science | SciFindern |
Citation search tips:
Search SciFindern, Reaxys (use the Query Builder), PubMed, Web of Science, Scopus, and Google Scholar for articles citing "Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis," by Beatty and Stephenson, (Accounts of Chemical Research, 2015, 48(5), 1474-1484). Compare the results. Why do they vary so much between databases?