Google Books is another good place to look. For some books you can read the entire book. For others you can see a preview of the inside of the book.
Use books to find historical information, in-depth research on a broad topic, tables of scientific information and more. Books can provide introductory and comprehensive information on your topic. Books are great sources because they have been rigorously edited and fact-checked before they get published. You will find high quality information in books. One thing to watch out for is the year the book was published; some books may not be current enough for your topic.