Visit their home pages. Have they digitized materials? If they haven't digitized, have they published Finding Aids (which give you a good sense of what materials are contained in their collections)?
When searching a database of books, whether the catalog or Google Books or WorldCat:
History of Women (on microfilm): Search the collection in the University of Oregon library catalog (search "history of women" and your topic, and limit your results to only items published before 1764). Limited amount available.