A Timeline Earl Raymond Hedrick 
E. R. Hedrick collection Archives of American Mathematics, Center for American History,The University of Texas at Austin  
Paul Ehrlich Kellogg, Bliss, Hedrick Mizzou Math Pioneers
Paul Ehrlich Hedrick in Missouri 
Virgil Snyder, Earle Raymond Hedrick, Science 97, 214 (1943)
Virgil Snyder, Earle Raymond Hedrick—In memoriam, Bull.