Frye, J.C.; Crawford, J.H.; Davis, S.N.; Donath, F.A.; Gloyna, E.F. & Krauskopf, K.B. Summary of geologic review group meetings, March 17--18, 1977 and May 26--27, 1977, report, July 18, 1977; (https://digital.library.unt.edu/ark:/67531/metadc690666/m1/2/: accessed April 23, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .