1. Agarwal, RP: Difference Equations and Inequalities: Theory, Methods, and Applications, 2nd edn. Dekker, New York (2000)
2. Jordan, C: Calculus of Finite Differences. Chelsea, New York (1956)
3. Krechmar, VA: A Problem Book in Algebra. Mir, Moscow (1974)
4. Levy, H, Lessman, F: Finite Difference Equations. Dover, New York (1992)
5. Mitrinović, DS, Kečkić, JD: Methods for Calculating Finite Sums. Naučna Knjiga, Beograd (1984) (in Serbian)