1. Ahlfors, L. V.Complex analysis, New York: McGraw-Hill 1966
2. Brolin, H., (1967) “Invariant sets under iteration of rational functions”,Arkiv für Matematik 6, 103–144
3. Cayley, A., (1879) “The Newton-Fourier imaginary problem”,Am. J. Math. II, 97
4. Cayley, A., (1879) “Application of the Newton-Fourier Method to an imaginary root of an equation”,Quaterly Journal of Pure and Applied Mathematics XVI, 179–185
5. Cayley, A., (1890) “Sur les racines d’une équation algébrique”,CRAS 110, 215–218