I'm quite often asked about recommending a good apple tree book. Especially about training and grafting.
There are hundreds out there, some great, some not. One I often recommend is form the 1940's, Fruit Tree Growing by Raymond Bush (if there was ever a name for a fruit tree book). Not everything in there is gold (they're just getting into sprays and stuff), but the chapter on grafting is good.
Although it's old it written in quite a light and humorous way, with instructions that are easy to follow. There are of course many other techniques out there, but this has a good handle on the basics. Also it shouldn't cost more than about £3 so I'm not recommending to someone to spend a fortune.
One thing I will say is that with fruit tree growing, grafting and training, it's just to have a go. You can pick up a cheap supermarket fruit tree for £5 most springs so it's worth buying one and just seeing how you can implement the knowledge in these book. Stuff normally grows back and they're surprisingly hard to kill (so long as you keep watering them). It's worth getting a few and having them in pots on the patio, make a framework of bamboo (hazel even better) and then just train them over a few summers into different shapes.
The same with grafting, make some family trees, try budding in late summer, cut a branch off an older tree and try to cleft graft. Invest a few pounds and buy some rootstocks on the internet and create your own trees, if they take you can sell them easily and cover your costs and you will have learnt far more than if you just read about it.
In fact after writing this I think I will get a few cheap apple trees and train them in pots on the patio to show how to do this. Should be fun.
Do you have fruit tree book you recommend or turn to?