Here are some suggestions for reference sources at the library that may be related to your topic. Some are print sources and some are available online. For print, you'll need the call number & location to find it. For online, you should be able to click the link to connect.
If these are not the sources you are looking for, you can search for other reference sources. Do a keyword search using "reference", "black", "African-American" or "white supremacy", and perhaps another more specific key word such as "activism" or "literature" or whatever your more specific topic is. When you look through your list of results, look for buzzwords like encyclopedia, almanac, or handbook. Those often denote reference sources.