Geological Survey (U.S.). Geologic Investigations of Radioactive Deposits, Semiannual Progress Report: June 1 to November 30, 1954, report, December 1954; (https://digital.library.unt.edu/ark:/67531/metadc1050455/m1/1/: accessed March 23, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .