[Letter from Brotherhood of Locomotive Firemen and Enginemen to W. S. Miller, March 21, 1955], letter, March 21, 1955; (https://texashistory.unt.edu/ark:/67531/metapth1150663/m1/1/: accessed July 9, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .