Martin, John H. (John Holmes), 1893-. Harvesting grain sorghums.. Washington, D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc6458/. Accessed May 18, 2013.
Martin, John H. (John Holmes), 1893-. Harvesting grain sorghums.. Washington, D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc6458/. Accessed May 18, 2013.