I often discuss with fellow entrepreneurs which books have helped them the most. Here is the top list of the Top 7 Startup Books of me and my friends.

• Eric Ries: The Lean Startup
  Fundamentals of getting a startup going. Of all the books in this list, start with this one.
• Peter Thiel, Blake Masters: Zero to One: Notes on Start Ups, or How to Build the Future
  Thoughts on how to create actual value as a startup. Peter Thiel and Blake Masters manage to actually bring in a perspective that’s a little bit different – this really helped me to come up with some new thoughts on my startup. +1 to the book for having Peter Thiel sign my copy at the Web Summit in Dublin. 🙂
  
• Chris Anderson: The Long Tail: Why the Future of Business is Selling Less of More
  The magic behind the business model of market places like Google (company), Amazon, or Spotify. Highly insightful, and New York Times bestseller for a reason (it’s really fun to read!). Inspired us to open up the “Long Tail” of sports sponsorship with our company Sponsoo
  
• Harper Lee: To kill a Mockingbird
  I don’t like that these lists only include business books. There’s so much entrepreneurs can learn from Harper Lee’s famous novel. The protagonist in To Kill a Mockingbird stands up for his beliefs and follows through with his vision even when his life and his family it as risk.
  
• Daniel Kahneman: Thinking Fast and Slow
  Basics on psychology, and how to avoid mental traps, by Nobel Laureate Daniel Kahneman. Fun fact: While reading the book, I emailed him on his Princeton address, explaining how I disagreed on one of his observations (happy to go into detail on this in the comments). I got a response from him with his view on the issue just 3 minutes later. +1 to him for being approachable.
  
• Robert Cialdini: Influence: The Psychology of Persuasion
  Learn the psychology behind sales. I remember that I just randomly picked this book up at Cambridge Judge Business School’s library, and then was amazed how helpful it actually was!
  
• Ken Blanchard: The One Minute Manager Meets the Monkey
  Simple guide on how to lead people. Quick and entertaining read.
  

I hope this helps! Please feel free to add any more suggestions in the comments.