TWW is a great book.

Another book on the TPS: https://www.amazon.com/dp/0915299143

I would look beyond books to seek out great organizers, leaders, and organizations in manufacturing. Dell is another good example. There are many others spread around the world.

If you are interested in the root of this methodology, consider reading Toyota Production System by Taiichi Ohno. Page 17 starts the discussion on how asking Why Five times is a method of determining root cause. This book isn't popular, but is worth your time.

http://www.amazon.com/Toyota-Production-System-Beyond-Large-...