Ryan, B.A. & Halas, D.R. de. Graphite burnout, interim report on IP-25-A (PT-105-532-E), report, March 15, 1960; (https://digital.library.unt.edu/ark:/67531/metadc679039/m1/1/: accessed November 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .