The Hathi Trust Digital Library is an online archive of content in and out of copyright. They receive content from Google, Internet Archive, Microsoft, and other partnering institutions. This site can be useful for genealogy research. You can search for an ancestor by surname or by collections. Searches can be made by Material type (book, periodical, etc.) or Language (many languages) or year range.

Here’s a link to the Search Tips page for better search results: Hathi Trust Digital Library Search Tips.