1. M. Kuczma, Functional equations in a single variable, Monografie Mat. 46, PWN, Warszawa 1968
2. Continuous and differentiable iteration semigroups;Zdun;Pr. Nauk. Uniw. Śl. Katow.,1979
3. Topics in iteration theory;Targonski,1981
4. Iterative functional equations;Kuczma,1990
5. Cocycles of continuous iteration semigroups;Guzik;Bull. Polish Acad. Sci. Math.,2003