Geological Survey (U.S.). Gordonville Quadrangle. Reston, Virginia. The Portal to Texas History. http://texashistory.unt.edu/ark:/67531/metapth108433/. Accessed June 18, 2013.
Geological Survey (U.S.). Gordonville Quadrangle. Reston, Virginia. The Portal to Texas History. http://texashistory.unt.edu/ark:/67531/metapth108433/. Accessed June 18, 2013.