Yep there is a volume two of that series. Its subtitle is "A Comprehensive Guide to the Identification and Care of Tropical Marine Invertebrates"
General Reef Books:
The Conscientious Aquarist by Robert Fenner
The Natural Reef Aquarium by John Tullock
Reef Invertebrates by Anthony Calfo and Charles Delbeek (this one covers not only inverts but lots of general "keeping a reef" type information, I consider it one of the best books out there)
ID/species books:
Aquarium Corals by Eric Borneman
Invertebrates by Julian Sprung
Giant Clams in the Sea and the Aquarium
And just for fun/informational type reading Coral Magazine can't be beat. Lots of neat articles in each issue.