What book to buy? Your recommendations please!

[Billy Zhao]

My work is kind enough to give allowance to buy personal improvement items up to $500 during the work from home time. Instead of buying a standing desk, I decided to use the money to buy some books. 

Can you recommend the most useful books for real estate investors from beginner to advanced? I assume some books are more for introduction and inspiration (Rich Dad Poor Dad, etc.) and some are very useful as a reference and tool (Gallinelli's Cashflow and key financial measures book). 

Thank you!