1.
Croft, T., Davison, R.: Foundation maths. Prentice Hall, Harlow (2010).
2.
Croft, T., Davison, R.: Foundation maths. Pearson/Prentice Hall, Harlow (2010).
3.
Rosen, K.H., Krithivasan, K.: Discrete mathematics and its applications. McGraw-Hill, New York (2013).
4.
Spector, L.: TheMathPage Skill in Algebra, http://www.themathpage.com/alg/algebra.htm.