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What are the best books on the subject of X?
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The best books on the subject of X will vary depending on your individual interests and needs. Some popular titles include "The Art of War" by Sun Tzu, "On Writing Well" by William Zinsser, "The Lean Startup" by Eric Ries, "The Innovator's Dilemma" by Clayton Christensen, "The Power of Now" by Eckhart Tolle, and "Zero to One" by Peter Thiel.