Performance of a 28-inch ramjet utilizing gaseous hydrogen at a Mach number of 3.6, angles of attack up to 12 degree, and pressure altitudes up to 110,000 feet, report, May 19, 1958; (https://digital.library.unt.edu/ark:/67531/metadc64063/m1/1/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .