1. An Introduction to the Theory of Numbers;Hardy,1979
2. Fascinating Fractions;Beskin,1980
3. Continued Fractions;Olds,1963
4. Analytic Theory of Continued Fractions;Wall,1948
5. Length of the period of a quadratic irrational;Podsypanin;Zap. Nauchn. Sem. Leningrad. Otdel. Mat. Inst. Steklov (LOMI),1979