Difference equations

Levi D, Winternitz P, Continuous symmetries of difference equations, JPA 39, R1 (2006)

Winternitz P, Symmetries of discrete systems, nlin/0309058

Agarwal R P, Difference equations and inequalities: theory, methods, and applications (Dekker, 2000), 2ed

Шарапудинов И И, Многочлены, ортогональные на сетках: Теория и приложения (Махачкала, 1997)

Никифоров А Ф, Суслов С К, Уваров В Б, Классические ортогональные полиномы дискретной переменной (Наука, 1985)

Wimp J, Computation with recurrence relations (Pitman, 1984)

Jordan C, Carver H C, Calculus of finite differences (NY, Chelsea, 1950)

Continued fractions

Lorentzen L, Waadeland H, Continued fractions with applications (NH, 1992)

Jones W B, Thron W J, Continued fractions: аnalytic theory and applications (Addison-Wesley, 1980)