Black Thought and Culture
"Contains 1,297 sources with 1,098 authors, covering the non-fiction published works of leading African Americans. Where possible, the complete published non-fiction works are included, as well as interviews, journal articles, speeches, essays, pamphlets, letters, and other fugitive material."
Google Book Search
If the book is out of copyright, or the publisher has given permission, you'll be able to see a preview of the book and, in some cases, the entire text; free online.
Women and Social Movements in the United States, 1600-2000
"A resource for students and scholars of US History and US women's history. The collection currently includes 108 document projects and archives with almost 4,300 documents and more than 150,000 pages of additional full-text documents, written by more than 2,200 primary authors."