I like 'The Inner Game of Tennis'
not technique stuff at all, but useful.
I taught myself to play with 'Lawn Tennis the Australian Way' as a child, but I don't think it is relevant anymore.
5.0 all courter. Betting the house on black 7 spades.. (Volkl X-7 310 WITH CYCLONE @ 55)
"Tennis isn't easy" - Corners