Before locating original records, genealogical researchers may find it useful to do a "literature review". This involves identifying any books, articles, or manuscript collections that have already been produced relating to the individuals or families of interest.
Articles: The journals, magazines, and newsletters that have been published within the genealogical community (many by national, state, and local genealogical societies) contain numerous articles that may relate to a researcher's family of interest. The best way to locate this material is to use PERSI, an online database that is made available via the subscription service Findmypast.
Manuscript collections: Unpublished materials, such as collections of letters, diaries, photographs, and miscellaneous papers and documents, may be part of the archive of a library or other special collection. WorldCat can be used to locate this material.