Fan Chung, the author of the oft-cited text Spectral Graph Theory has posted, among other things, a series of lecture notes on the subject. I'm posting this specific link for quick reference--it's otherwise hard to find in the maze of content on her site.
I read the book on Erdos some years ago. Featured too were two mathematicians, a juggler and his Taiwanese-born wife. The wife, I believe, was Fan Chung.