Evvard, John C. & Wyatt, DeMarquis D. Investigation of a variable Mach number supersonic tunnel with nonintersecting characteristics, report, November 15, 1948; (https://digital.library.unt.edu/ark:/67531/metadc64572/m1/2/: accessed November 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .