Biggs, Norman. 1989. Discrete Mathematics. Rev. ed. Oxford: Clarendon.
Grimaldi, Ralph P. 2014. Discrete and Combinatorial Mathematics: An Applied Introduction. Fifth edition. Harlow, Essex, England: Pearson Education Limited. https://www.vlebooks.com/vleweb/product/openreader?id=AberystUni&isbn=9781292035994.
Liu, C. L. 1985. Elements of Discrete Mathematics. 2nd ed. Vol. McGraw-Hill computer science series. New York: McGraw-Hill.
Wilson, Robin J., and John J. Watkins. 1990. Graphs: An Introductory Approach: A First Course in Discrete Mathematics. New York: Wiley.