Davis, Donald Jack & McCarter, William. [Letter from Bill McCarter and Jack Davis to Don R. Roberts, March 26, 1991], letter, March 26, 1991; (https://digital.library.unt.edu/ark:/67531/metadc1039968/m1/1/: accessed March 22, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .