Geology of the forty-ninth parallel sheet no. 4, map 77 A
Geology of the forty-ninth parallel sheet no. 4, map 77 A, map, 1913; [Ottawa, Ontario, Canada]. (texashistory.unt.edu/ark:/67531/metapth187398/: accessed December 15, 2017), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; crediting University of Texas at Arlington Library.