What's Your Favorite Book That Helped You on Tac?

I'm televon your favorite book that helped you on tac i know you have it a a. A by ron hefitz he's a harvard professor. And his whole thesis of this book is that there are a different types of challenges and changeare these technical changes that you can make where you already know basically how to do this. There are other changes which are called adaptive, which require thinking, learning and behaving in completely different ways.