Amundson, P. I.; McVean, R. L. & Long, J. K. A Two-Zone Fast Critical Experiment (ZPR-III Assembly 42), report, January 1, 1964; (https://digital.library.unt.edu/ark:/67531/metadc871336/m1/1/: accessed November 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .