Allen, R. P.; Arrowsmith, H. W. & Nelson, R. D. X-Ray Comparison of Beta Plutonium Grain Size., report, January 1, 1971; (https://digital.library.unt.edu/ark:/67531/metadc869062/m1/1/: accessed April 26, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .