Most of my 120 zoo guidebooks have been obtained via trades with overseas ZooChatters or from Ebay, but here is something that I posted on this forum recently:
I've now purchased 10 guidebooks from Beckon Books and I'd highly recommend all of them to anyone who actively collects zoo memorabilia. The publications are large, glossy and colourful, and the Shedd & Georgia guidebooks are hardcover as an added bonus. Chris Capen, the President of Beckon Books, has been hugely supportive of the zoo literature industry and via several emails and a phone call he went out of his way to put together a superb package of books to send to my Canadian home. He has assured me that there are even more zoo guidebooks due in the next few years and I'll be first in line to order them as soon as they are published.
Here are the 10 that I own:
San Diego Zoo: Elephant Odyssey
San Diego Zoo: Panda Trek
San Diego Zoo: 100 Extraordinary Images
San Diego Zoo Safari Park (146 pages including the cover)
Cleveland Metroparks Zoo
Philadelphia Zoo
Phoenix Zoo
New England Aquarium
Shedd Aquarium (100 pages including the cover)
Georgia Aquarium