Chang, S. J.; Carpenter, J. A. & Altom, D. W. Viscoelastic Analysis of Irradiated Graphite With Variable Creep Coefficient., report, January 1, 1971; (https://digital.library.unt.edu/ark:/67531/metadc865719/m1/1/: accessed September 23, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .