Below are links to online reference sources and collections that are most useful for this subject. These sources are useful for their bibliographies; additional events, organizations, and people to search; and ideas for research topics:
You can search the Historical Thesaurus (use the drop-down menu directly to the left of the search bar) to explore the different words used for a particular concept or meaning over time. Note that when searching for words related to race and ethnicity, or to other social identities, you may encounter derogatory language.