The CIA museum has a very useful short history. although it does not mention that maps very similar to the one in the book were given to helicopter pilots during the Vietnam War. Another site provides good information on different US Military’s silk maps,. even though the design of the site is somewhat busy.
Silk maps hidden in monopoly boards
during WWII aimed at aiding Allied POWs escape. A very interesting read and helps to give an understanding of the practicality of printing maps on silk. Very accessible, quick, and easy read.
Extensive History of World War II in Southeast Asia
A detailed overview of activities in South East Asian Theater during WWII from a course offered at Northern Illinois University.
Map below shows the area covered in the Silk Map appearing in the book/
View Indochina in a larger map