Although not necessarily written on sales, I think The Tipping Point by Malcolm Gladwell would be helpful.
-------------------------
AllBallz.Net - For Sports Balls From A to Z.
I was brought up on Brian Tracy`s Psychology of Selling many years ago and have referred back to it on occassion. I would also recommend finding a mentor and being accountable to that person.
To your success,
Any of the SPIN selling books, I know I am one of the many recomending them, but they are incredible
I am also looking for more books to read on this topic so far i have read 4 books in the past few months on selling and I have started two more. I can not get enough of this stuff, it is so valuable.