Concordia College Board of Control. [Letter from Concordia College Board of Control to William Hagen, March 5, 1930], letter, March 5, 1930; (https://texashistory.unt.edu/ark:/67531/metapth494643/m1/1/: accessed July 9, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .