The best books for apartment investors depend on the investor's experience level and goals. For beginner investors, Real Estate Investing for Beginners: The Complete Guide to Investing in Real Estate by Brandon Turner is a great place to start. For more experienced investors, The Book on Investing in Real Estate with No (and Low) Money Down: Real Life Strategies for Investing in Real Estate Using Other People's Money by Brandon Turner is a great resource. Additionally, The Millionaire Real Estate Investor by Gary Keller is a great book for investors looking to build wealth through real estate.