As the title says, Dale Carnegie's, How to Win Friends and Influence People.
As it applies to PU, this book could have been renamed, How to Maximize your social proof. All the tools to use point people to your advantage. Have people like you, change their minds, and gain respect. It's not about girls; it's about creating a healthier social life. For guys who claim to have no friends or think there is something wrong with their personality as well.