Texas. Department of State Health Services. Texas EMS Magazine, Volume 30, Number 6, November/December 2009, periodical, December 2009; (https://texashistory.unt.edu/ark:/67531/metapth1507903/m1/9/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .