Good Books?

In order of how often they are used, here's a list of the reference books I have, if there are any I absolutely should get, I would appreciate the advice very much.
Barron's:
The Natural Aquarium Handbook
Tropical Fish
The Barb's Aquqrium
Cichlids
Bettas

I am looking for a good book on fish diseases and treatments, and a guide for keeping plants in an aquarium as well. There are so many out there and even when the publisher's the same they can have contradictory information. Thanx in advance.

Hi there,
I can recommend an exceptional book on fish health.
It is:
Manual of Fish Health
Dr. Chris Andrews, Adrian Exell, and Dr Neville Carrington.
2003, Firefly Books, Toronto, Ont.
I purchased it at Bolens Books, In Victoria BC, for about $15-20.00
The information in it is right, the treatments high quality,
and has wonderful color illustrations of diseases, as well as
information on disease prevention.