There are a lot of great online book sites but my favorite is the free book collection at MyHeritage.
The have over 400,000 books and their search engine does a great job providing results. If you’re going to spend a few minutes looking for an ancestor in a book collection, try this one first.
The book collection is officially called “Compilation of Published Sources” and the description says, “This collection includes a compilation of thousands of published books ranging from family, local and military histories, city and county directories,school, university and hospital reports, church and congregational minutes and much more. All records include images of the book’s pages. We are continually growing this collection.”