Pinter, Charles C. (1990). A Book of Abstract Algebra. Retrieved from http://www2.math.umd.edu/~jcohen/402/Pinter%20Algebra.pdf
Judson, Thomas W. (2015). Abstract Algebra Theory and Applications. Retrieved from http://abstract.ups.edu/download/aata-20150812.pdf
Cornell. (February 7, 2006). Everything You Need to Know About Modular Arithmetic. Retrieved from http://pi.math.cornell.edu/~morris/135/mod.pdf
Tylor, Richard. (2012). Modular Arithmetic: Driven by Inherent Beauty and Human Curiosity Retrieved from https://www.ias.edu/ideas/2012/taylor-modular-arithmetic
Neale, Vicky. (2011). An Introduction to Modular Arithmetic. Retrieved from https://nrich.maths.org/4350
Cangelosi, James S. (2019). Meeting #1 – #25: Definitions, Shorthand Notations, & Theorems. Retrieved from https://usu.instructure.com/courses/532374/pages/definitions-axioms-and-theorems
Lewand, Robert. (2000). Cryptological Mathematics. (Pp. 27-44). Retrieved from https://usu.instructure.com/courses/532374/files/72064328/download?wrap=1
Khan, Sal. (n.d.) Journey into cryptography. Retrieved from https://www.khanacademy.org/computing/computer-science/cryptography
AOPSonline. (n.d.) Modular arithmetic/Introduction. Retrieved from https://artofproblemsolving.com/wiki/index.php/Modular_arithmetic/Introduction
Ms-Academy. (2016). Modular Arithmetic & Fermat’s Little Theorem. Retrieved from https://www.mathacademytutoring.com/modular-arithmetic-fermats-little-theorem/
War of Secrets: Cryptology in WWII. (2015). Retrieved from https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196193/war-of-secrets-cryptology-in-wwii
Modular Arithmetic. (n.d.). Retrieved from http://www.math.utep.edu/Faculty/tuesdayj/math210g/ISBNUPCMoney.pptx
Taylor , R. (2012). Modular Arithmetic: Driven by Inherent Beauty and Human Curiosity. Retrieved from https://www.ias.edu/ideas/2012/taylor-modular-arithmetic