Jamieson, Dave (April 1, 2010). "The great changemaker". Mint Condition: How Baseball Cards Became an American Obsession. Open Road + Grove/Atlantic. pp. 89–. ISBN978-0-8021-9715-3.
Mullin, Bernard James; Hardy, Stephen; Sutton, William Anthony (2007). Sport Marketing (3rd ed.). Champaign, Illinois: Human Kinetics. p. 197. ISBN9780736060523. OCLC74941202. Retrieved January 15, 2020.
Mullin, Bernard James; Hardy, Stephen; Sutton, William Anthony (2007). Sport Marketing (3rd ed.). Champaign, Illinois: Human Kinetics. p. 197. ISBN9780736060523. OCLC74941202. Retrieved January 15, 2020.