APA (7e ed.) Bronvermelding

Walker, A. L., Roach, J. K., & Hanna, J. M. (1967). How to use adding and calculating machines: Full-keyboard adding machine, ten-key adding machine, printing calculator, rotary calculator, key-driven calculator (3rd ed.). Gregg Division, McGraw-Hill.

Chicago (17e ed.) Bronvermelding

Walker, Arthur L., J. Kenneth Roach, en J. Marshall Hanna. How to Use Adding and Calculating Machines: Full-keyboard Adding Machine, Ten-key Adding Machine, Printing Calculator, Rotary Calculator, Key-driven Calculator. 3rd ed. New York: Gregg Division, McGraw-Hill, 1967.

MLA (9e ed.) Bronvermelding

Walker, Arthur L., et al. How to Use Adding and Calculating Machines: Full-keyboard Adding Machine, Ten-key Adding Machine, Printing Calculator, Rotary Calculator, Key-driven Calculator. 3rd ed. Gregg Division, McGraw-Hill, 1967.