Specialized search engines

Google Scholar works well for fields that are paper-oriented and have an online presence in all (or nearly all) respected venues. Most papers written by computer scientists will show up, but for less technologically current fields, representation in Google Scholar is less reliable. Even the journal Science only puts articles online back to 1996. Thus, Google Scholar should rarely be used as proof of non-notability.

Medline, now part of Pubmed, is the original broadly-based search engine, originating over four decades ago and indexing even earlier papers. Thus, especially in biology and medicine, Pubmed "associated articles" is a Google Scholar proxy for older papers with no on-line presence. E.g., The journal Stroke puts papers on-line back through the 1970's. For this 1978 paper ,Google Scholar lists 100 citing articles, while Pubmed lists 89 associated articles

There are a large number of law libraries online, in many countries, including: Library of Congress, Library of Congress (THOMAS), Indiana Supreme Court, FindLaw (USA); Kent University Law Library and sources (UK).