Castles, Walter JR.: A Direct Method of Calculating the Maximum Rate of Climb, Top Speed and the other Useful Performance Characteristics of a Helicopter in Powered Flight, January 1944

Castles, Walter JR.: A Direct Method of Calculating the Maximum Rate of Climb, Top Speed and the other Useful Performance Characteristics of a Helicopter in Powered Flight, January 1944, SERIES 2, Box: 5, Folder: 9. School of Aerospace Engineering records, UA328. Archives and Special Collections, Library, Georgia Institute of Technology. https://finding-aids.library.gatech.edu/repositories/2/archival_objects/4588 Accessed September 16, 2024.