Good background information may be found in reference sources, like Credo Reference.
Reference sources (dictionaries, encyclopedias, manuals, guides) provide the following types of information on virtually any topic:
Find additional reference sources by searching Bishop Library's Catalog. Click on Advanced Search, choose Type, choose Reference.
Image Source: Advertisement for slave sale. New Orleans, May 13, 1835. New York Historical Society #46628, as shown on slaveryimages.org, compiled by Jeromy Handler and Michael Tuite and sponsored by the Virginia Foundation for the Humanities and the University of Virginia Library.
Print subject encyclopedias available in Bishop Library.