My war torn copy.
I spent the last few months looking like a total dork reading this book on the train. But I'm a rockstar when I get to my client's office thanks to much of the information found in this resource.
The book doesn't just give you scenarios and how to react to them, rather it helps you to think analytically when facing certain SQL Server symptoms. Places to start and then you use your understanding of the process to direct the next troubleshooting steps.
After reading through it cover to cover, I still use it as a reference manual. (There's no way I can remember everything!) But I'll remember that the problem I'm facing was mentioned somewhere in the book and I can just flip to right section and have a place to start.
I've seen the author, Grant Fritchey ,speak on a couple of occasions. He's depth of knowledge goes even beyond this almost 1000 page book.
Learning is a funny thing in that, the more you actually learn, the more you realize you don't know.
You can find a copy of the book here. Though I've been told that the author is in the process of updating it with relevant information for SQL Server 2017. I'll be sure to pick up a copy when that comes out as well.