99 critical shots is a good book, but its directed at 14.1. it seems. I guess 14.1 is usable in all facets of the game. what about for the advanced player??
You didn't specify for advanced player in your original question. You mentioned to advance your play and drills.
The reason I liked the Byrnes books over 99 critical shots was purely in the interest of the beginner. 99 book is an outstanding resource book and refresher book for the intermediate player, but for the beginner, who understands very little and disects the graphics in the book to see the shots, the graphics are terrible.
Whomever was the illustrator in 99 shots did that book an unfortunate injustice by scaling the table layouts so badly out of proportion, that the true beginner only ends up confused with examples of balls that don't pass other balls and angles that portray misinformation.
For those of us that understand the concepts being shown, it is practically unnoticeable, but for the beginner, the illustrations are very poor at best.
Not to detract from Rays content when I say this, because his may be the most complete in that regard, but nevertheless, for a true beginner I'd not recommend it as my first choice.
As far as an advanced player goes, I believe the game is far more cerebral than mechanical or physical. In that respect, The Inner Game of Tennis, Pleasures of Small Motions, and an extremely high dose of straight pool would be my suggestions.