Aerial Radiometric and Magnetic Reconnaissance Survey of Baltimore, Washington, and Richmond Quadrangles: Volume 2-C. Richmond Quadrangle, report, September 1978; (https://digital.library.unt.edu/ark:/67531/metadc958207/m1/1/: accessed July 17, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .