You haven't said whether you mean fiction or fact so I'll go for both in no particular order

I don't really have favorite training books so you won't find any in this list! Most of these are oldish books,
Endal and
the working lurcher are the exceptions.
Fiction:
Lassie come home, by Eric Knight. If you have only read the mimics or watched the films you have never met Lassie. You have to READ how she arrives at the school gate.
The Incredible Journey, by Sheila Burnford, I read this again and again as a child, the words are so simple yet the story so poignant, I always cry, especially when Luath makes his so painful retrieve and also when Bodger doesn't make it back with the others! It beats all of the films hollow.
Bel Ria is by the same author, funny in places but terribly sad, I won't read it again.
Where the red fern grows, by Wilson Rawls, a story about a boy, his family, his two redbone hounds and their adventures hunting racoons.
Spy the no good pup, by Joyce Stranger, the story of two struggling hill farmers and how their training of a border collie pup to be a sheepdog goes wrong - oh so easily - but help comes all of them eventually. Also
Gelert and other stories, by the same author, as a child I really identified with the Gelert story because the boy, Barry wanted a dog (specifically a GSD) and couldn't have one and he tries so hard to fill the gap with other peoples dogs and can't.
Cop Shooter, Kit Higson. A story about a half dead mongrel pup that is rescued from a dustbin and raised by a small boy in defiance of his unpleasant Aunt! Cop grows to be a big poodlelike dog and gets stolen. Boy and dog eventually get the perfect happy ending living by the sea in Cornwall (without the Aunt).
Scrub, dog of Alaska and
Home is the North by Walt Morey, each is a story about a boy and his life in the north with his dog.
Fact:
Endal, by Allen Parton. The story of a service dog that really knew what it was doing!
The Working Lurcher, by Brian Plummer. Fascinating anecdotal read for people with lurchers. I didn't say I agree with all the content nor do I vouch for it's truth, lurcher lore is often a tall story

.
Three's a Pack, by Joyce Stranger. We had a psycho dog, this book helped us to realise that it isn't always the owners fault. Joyce Stranger was used to dogs, had dogs, trained dogs. Someone gave her a GSD pup as a present (she did not approve but had to do what she could with the pup). It howled like a banshee for weeks, it was from a hyperactive strain of GSD's, I think the rest of the litter ended up destroyed. The training methods might not sound right to us now but she worked with what was there at the time and that dog eventually competed in obedience trials.
Ajax the Warrior, by Mary Elwyn Patchett. Based on the authors own childhood this is the story of a girl and her family and pets in the Australian outback. Ajax dominates the story, a dingo cross that she rescued as a pup grows up to be her devoted friend and defender - against anything that threatens her and her home, whether against robbers or cattle killers, whether she faces drowning or 3 starving wolves escaped from a circus Ajax is first to protect her even if it costs his own life.
Okay maybe I'd better stop now, I keep thinking of more books... Oh no I just thought of
Hi fella, Era Zistal, how a lost puppy wanders in the wilderness befriending and losing other animals (including a racoon and a wild cat) along the way until eventually he finds people who will care for him. I loved that story!
That's it, I quit!