Notes by Dr. Christopher Lovejoy
Full name: The Mom Test: How to talk to customers & learn if your business is a good idea when everyone is lying to you
How strongly I recommend it: 9/10 Read more on Amazon
This book changed my perspective on how to talk to customers to develop and improve your business idea. If you're starting or running a company and only want to read one book on the subject, I think this should be the one. Most applicable for direct-to-consumer businesses, but contains learnings that are still useful for other business types.