Malvestuto, Frank S., Jr. Method of estimating the minimum size of a tail or wing-tip parachute for emergency spin recovery of an airplane, report, October 27, 1948; (https://digital.library.unt.edu/ark:/67531/metadc62840/m1/1/: accessed October 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .