The Minto Pyramid Principle: Logic in Writing, Thinking, & Problem Solving by Barbara Minto (http://www.amazon.com/Pyramid-Principle-Writing-Thinking-Pro...)

Some Mental Models are available here for free :

http://www.focusinvestor.com/FocusSeriesPart3.pdf

http://www.focusinvestor.com/MungerModels.pdf

For systems :

Lean Thinking by James Womack

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Some thought provoking personal effectiveness titles :

The Four Agreements by Miguel Ruiz (http://www.amazon.com/Four-Agreements-Practical-Personal-Fre...)

The Paradox of Choice: Why More Is Less by Barry Schwartz (http://www.amazon.com/Paradox-Choice-Why-More-Less/dp/006000...)

The Power of Full Engagement by Jim Loehr and Tony Schwartz