“The Roots of Lean. Training Within Industry: The Origin of Japanese Management and Kaizen”, by Jim Huntziger. www.lean.org/Community/Registered/ArticleDocuments/Roots%20of%20Lean%20-%20TWI.pdf [obsolete link]
Tom Poppendieck pointed this out on one of the lists. It’s an article on how a WWII effort called “Training Within Industry” was the basis for the “kaizen” continuous improvement approach in the Toyota Production System.
[Update 2021-09-25: That link is obsolete; here’s a new link.]