Sun Tzu 
The Art of War [EPUB ebook] 

The Art of War is one of the oldest and the most influential text of warfare. Comprising of 13 chapters, each devoted to a different set of skills used in warfare, the book gives a detailed explanation and analysis of the Chinese military, from weapons and strategy to rank and discipline.
The tactics in the book have also been applied to many fields outside of the military. It has become a training guide for many competitive endeavors that do not involve actual combat.