I've gotten many books (well, really like 7) including Dr. Axelrods' marine and freshwater Atlases (¿?). To be honest, in all my books, there was nothing I didn't already know from visiting this forum and researching the Internet. This proves to be true except for the s fw stingrays books.
Yesterday, I started to read Complete Encyclopedia of the Saltwater Aquarium Nick Dakin. It covers the basics of an saltwater aquarium and it also compares it (in a very light way) with FW aquarium keeping. It's a nice feature.
Thus far, my favborite is Encyclopedia of Aquarium and Pond Fish by David Alderton, for it covers both marin and freshy aquariums, and ponds. It has a bief description of many plants and their set up. Nice book.
Most of my books have been ordered trough AMAZON, which isa great source.