Advanced Tennis by Paul Metzler
Mental Tennis by Vic Braden
Match Play and Spin of the Ball by Bill Tilden
Tennis Tactics by USTA
Pressure Tennis by Paul Wardlaw
These are all on the tactical or mental side of the game, as opposed to focusing on technique. I'll echo the sentiment that Winning Ugly is also a worthwhile read.
Just a thought, but if you have enough money to buy books, you probably have enough for lessons. In today's economy, I've seen all sorts of imaginative accomodations to keep pros busy that you never would have encountered a few years ago. For example, the club pros here, which tend to be more pricey, are charging a flat hourly rate for up to four people. Go with one of the assistant pros and that's about $35/hr split up to four ways. Fairly easy and relatively inexpensive to set up a group lesson that could be run like a mini-clinic, focusing less on technique and more on patterns of play.
Public recreation departments usually hire younger, less experienced pros because they cost less. They generally don't charge as much for private lessons as well. Depending upon your needs, public programs can be a good value. Of course, as in most things, you get what you pay for, so adjust your expectations accordingly.
Good luck and good reading! Cheers!
