[72nd Texas Legislature, Regular Sessions, House Bill No. 638]
[72nd Texas Legislature, Regular Sessions, House Bill No. 638], legislative document, March 1991; Austin, Texas. (https://texashistory.unt.edu/ark:/67531/metapth1261349/: accessed December 4, 2020), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting Private Collection of Mario Marcel Salas.