What is amazing in the world of dog books (of which there are thousands!) is people keep coming up with great ideas for books exploring new ways of training and caring for dogs. What is equally amazing is the longevity of a sizeable number of books that were written 15 or more years ago which remain very popular and are still considered required reading in the subjects they address.
The Culture Clash by Jean Donaldson (behavior/training).
Here are a bunch of them that meet those standards which if you have never read, you should! Please note that several of these are now in second or even third editions so the date of the book may be much newer:
Excel-erated Learning by Pam Reid (learning theory).
Give Your Dog a Bone by Ian Billinghurst (raw feeding).
Aggression in Dogs by Brenda Aloff (aggression).
Before and After Getting Your Puppy by Ian Dunbar (puppy training/socialization).
On Talking Terms With Dogs by Turid Rugaas (body language/calming signals).
Don't Shoot the Dog by Karen Pryor (operant conditioning/clicker training).
Canine Massage by Jean-Pierre Hourdebaigt (massage).
Therapy Dogs by Kathy Diamond Davis (therapy dog training).
The Other End of the Leash by Patricia McConnell (behavior/training).