[dmkirwan]

I assume you're not interested in hearing the obvious ones (zero to one, lean startup, etc., etc.) so I'll recommend two.

At the early stages when you're defining your strategy? "Good strategy/bad strategy" by Richard P. Rumelt. "Strategy" is thrown around a whole lot in business, often by somebody who is talking about a goal, as opposed to how to reach it. This book can get a little repetitive but the overarching teachings are valuable and will serve you well throughout your entrepreneurship journey.

After the startup phase (growth/acquisition)? I recommend "The messy middle" by Scott Belsky.

[hkhanna]

I read The Messy Middle and thought like the chapter titles were phenomenal, but felt everything in the actual chapters was fluff. Maybe I'll give it another try!

[collin128]

The messy middle was fantastic. Only reason I didn't list it in my comment below was that I read it recently and I'm 11 years in.

Highly recommend the book.