One of the most clearly written books on perspective is Ernest R. Norlings PERSPECTIVE MADE EASY. It is a basic fundamental sort of book on perspective, but it walks the reader through perspective extremely well. You can pick this book up on Amazon for around $9:
David Chelsea's PERSPECTIVE! FOR COMIC BOOK ARTISTS is pretty good too. It has a bit of that Scott McCloud formula to it, but there's a lot of valuable info in it:
Hope that helps, Eric!