jThinker is a free software, so everyone can use it! Moreover, it's so free that everyone can develop it as well!

However, to use it effectively you should know the Theory of Constraints ideas, without them jThinker is just a tool for drawing boxes. So, here I list several TOC books that I value high myself.

• Eliyahu M. Goldratt. The Goal: A Process of Ongoing Improvement. A very inspiring business novel that contains the core ideas of TOC. The book that any TOC practioner have to start with.

• Eliyahu M. Goldratt. Theory of Constraints. The fundamental book on application TOC to manufacturing processes. Includes the reference of thinking processes diagrams and all other stuff you'd better know for effective use of jThinker.

• H. William Dettmer. The Logical Thinking Process: A Systems Approach to Complex Problem Solving. A good reference on analytic thinking using thinking processes.

• Lisa J. Scheinkopf. Thinking for a Change: Putting the TOC Thinking Processes to Use Another good manual both on TOC fundamentals and on thinking processes application.

• David Allen. Getting Things Done: The Art of Stress-Free Productivity Not really TOC-related, but the best time-management book I've ever seen, so a definite "must read"