Welch, F.H. Thermal cycle, shock, acceleration and vibration testing of a BeO reflector specimen, part No. EX-N69626085, report, April 24, 1969; (https://digital.library.unt.edu/ark:/67531/metadc878544/m1/1/: accessed March 26, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .