Booklets? Not super familiar with the smaller ones.
For books -
Fundamentals by Bob Cassidy
13 Steps to Mentalism by Corinda
Practical Mental Magic by Annemann
That's a year or so of study there.
If you want to get really good - Scripting Magic by Pete McCabe, Maximum Entertainment by Ken Weber, Absolute Magic by Derren Brown, Pure Effect by Derren Brown, and Alchemical Tools by Paul Brook.
The thing to remember about mentalism is that it's not the same thing as magic. It requires a different theatrical approach, and also relies more on theatrical skills. With a magic trick you can just do the method and get reactions. With mentalism you have to have a good presentation, and you have to understand how to deliver that presentation.
Not saying one or the other is better, just that they are different.