Because of their nature, books can cover a subject both broadly and deeply. However, because of the time it takes to research, write, edit, publish, print and deliver books, a publication cycle can take anywhere from 6 months to many years. So, don't expect a book to always cover the most recent events or newest ideas. And not all books covering an academic topic are “scholarly” books, even if you found them in a college library. Always use your critical thinking skills to evaluate books for your research.
Use a Google Books search box to search for free ebooks. After doing a search click on "Free Google Ebooks" on the left hand side of the screen to limit all search results to free books. Use the Google Books search box below, or type https://books.google.com/ in a search engine to get to this Google tool: