Coles, Willard D & Callaghan, Edmund E. Full-scale investigation of several jet-engine noise-reduction nozzles, report, January 1, 1958; (https://digital.library.unt.edu/ark:/67531/metadc60812/m1/1/: accessed November 20, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .