Aspnes, James. (2022). Chapter 1. Notes on Discrete Mathematics. License: CC BY-SA: Attribution-ShareAlike.
Davis, Stephen. (2019). Chapter 1. A Cool Brisk Walk Through Discrete Mathematics, version 2.2. License: CC BY-SA: Attribution-ShareAlike.
Jamaloodee, Mohamed, et al. Chapter 2. Discrete Math. Georgia Gwinnett College, Accessed 19 January 2025. License: CC BY-NC: Attribution-NonCommercial.
Levin, Oscar. (2023). Chapter 0, Section 1 and Appendix C. Discrete Mathematics: An Open Introduction, https://discrete.openmathbooks.org/dmoi3/, 3rd edition. License: CC BY-SA: Attribution-ShareAlike.
Sassolas, Mathieu. (2021). Foreword. Introduction to Discrete Mathematics: An OER for MA-471, https://academicworks.cuny.edu/qb_oers/179/. License: CC BY-NC: Attribution-NonCommercial.