Of course Mark Douglas is an essential. It's a must because it sheds some light on the nature of this business. The probabilistic one .....
On the psych front: Mark Douglas is very good for understanding the fear related issues in trading and a method for approaching them (brute force). Steenbarger - Enhancing Trader performance is worthwhile from a modern (non-nlp) look at how to train oneself and overcome problems. People still say "i want to master/overcome/suppress my emotions (pick ur word)" which means they don't understand the brain. Download Denise Shull's presentations to round off the view.
however, Ari Kiev's book, although very intricate has one definitive chapter, i can't remember which one, in which it instructs traders how to meditate and practice "visualization" just like athletes do, practicing the exercise/trade in your mind in order to be ready to flawlessly execute it in real life. definitive read.