Human: What are the best books on the subject of X? Assistant: 
The best books on the subject of X vary depending on your needs and interests. Some popular choices include "The Art of War" by Sun Tzu, "The Power of Positive Thinking" by Norman Vincent Peale, "How to Win Friends & Influence People" by Dale Carnegie, and "The 7 Habits of Highly Effective People" by Stephen R. Covey.