Take a trip to the library. Use the electronic catalog or browse the shelves to look for books on your topic. If you find a book that is useful, check the bibliography (list of sources) in the back of that book for other books or articles on that topic. Also check indexes of periodicals and newspapers. Check with a librarian if you need help finding sources.
Try to use as many different types of sources as you can, including books, magazine articles, and internet articles. Don't rely on just one source for all your information.
Keep a list of all the sources that you use. Include the title of the source, the author, publisher, and place and date of publication. This is your preliminary, or draft, bibliography.