He references the 3.5 D&D reference work Cityscape.
As an FYI I am a member of the Scribd (online books, etc.) resource site and almost all older D&D have been uploaded there by users.
It goes without saying that you should only download material that you have hard copies of but being able to carry a tablet with all my rule books etc. on it instead of a backpack full of rule books has been awesome.