Recommended Reading The TWI Workbook: Essential Skills for Supervisors Buy Book Patrick Graupp and Robert J. Wrona, Productivity Press, 2016 Written in a practical, easy-to-understand style, this book is directed at first-line supervisors with a strong focus on learning how to put the TWI methods into use. In support of the book, Art Smalley, President of the Art of Lean, comments, “If companies would spend half the time developing these essential (TWI) skills in the supervisor ranks that they spend on conducting Value Stream Mapping or Kaizen Workshops, I am convinced that they would not only achieve more impressive results, but the results would stick better as well.