Otto, David to Madame Nguyen Thi Binh, letter of thanks and plea on behalf of prisoners of war, March 5, 1971, Box: 1, Page: 56. The Dr. David A. Otto, Special Envoy for the Missouri State Teachers Association during the time of the 1971 Paris Peace Talks, collection, RH MS 1257. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/32505 Accessed May 17, 2024.