Bruce (Focus and Leverage Consulting, USA) Nelson & Bob (Focus and Leverage Consulting, USA) Sproull 
Epiphanized [PDF ebook] 
A Novel on Unifying Theory of Constraints, Lean, and Six Sigma, Second Edition

Updating the tools, principles, and methods presented in the bestselling first edition, this updated edition explains how to implement the authors proven improvement methodology that unifies the Theory of Constraints with Lean and Six Sigma.