You can find more books and media under the following subject headings:
You can always try searching the William and Mary Libraries catalog and then narrow the Material Type to books, book chapters, or reference entries (this video is a refresher on searching the catalog; some of the details are different but the process remains the same). However, some of the specific background resources below may also be useful.
While W&M subscribes to National Geographic from multiple sources, the National Geographic Virtual Library is the best way to access it to see the full color photography.