What's Your Favorite Strategy Book?

There is a difference between strategy and tactics. And you know what? It's worth making that differentiation point here, because you and I have spent enough time in the industry to probably have taken that bit of knowledge for granted. But there will be folks in the chat today who haven't necessarily digested that all been exposed to that. Let's go to the next question from Paul, which is a little bit easier. He asks: What's your favourite strategy book? So books, resources, where do you go to digest and understand strategy?