J.M.
J.,
I am unclear, are you looking for a book for you or one for your son?
I am a homeday care provider with 2 of my own children and my best advice to you is to be firm but supportive and encouraging. Do not ASK if he has to go potty but tell him that it is time for him to go sit on the potty and see what he can do. Read him his favorite story or play a game with your shower curtain, anything to keep him distracted from what he is actually doing and then praise him like crazy...you could even try to give him an m&m when he goes without giving you any problems. In the beginning it is best to take him to the bathroom approximately every 30 minutes or even a little less if you notice that he is wet when you go, until he gets to know the feeling. At this point it is the parent and not the child that is being potty trained.
With a strong will on your part and a little cooperation on his he will be potty trained within a month, that is except for napping and nighttime.
I hope this helps, but I have trained many of kids this way and have never had it fail.
Remember be strong you are the boss and make sure he knows how proud of him you are.
GOOD LUCK!
J.