1. Babbage C., Examples of the Solution of Functional Equations, Cambridge, 1820
2. Bronshteĭn E.M., On an iterative square root of a quadratic trinomial, In: Geometric Problems in the Theory of Functions and Sets, Kalinin. Gos. Univ., Kalinin, 1989, 24–27 (in Russian)
3. Chen X., Shi Y, Zhang W., Planar quadratic degree-preserving maps and their iteration, Results Math., 2009, 55(1–2), 39–63
4. Choczewski B., Kuczma M., On iterative roots of polynomials, In: European Conference on Iteration Theory, Lisbon, 15–21 September 1991, World Scientific, Singapore-New Jersey-London-Hong Kong, 1992, 59–67
5. Decker W., Greuel G.-M., Pfister G., Schönemann, H., Singular 3-1-1 — A Computer Algebra System for Polynomial Computations, available at http://www.singular.uni-kl.de