1. L. Bieberbach, Analytic Continuation [Russian translation], Nauka, Moscow (1967).
2. W. J. Trzinsky, “On composition of singularities,” Trans. Amer. Math.,32, 196–215 (1930).
3. T. Shell-Small, “On the convolution of analytic functions,” J. Reine Angew. Math.,258, 137–152 (1973).
4. A. Yanushauskas, “Composition of singularities of functions in two complex variables,” in: Differential and Integral Equations. Boundary Value Problems [in Russian], Tbilis. Univ., Tbilisi, 1979, pp. 293–303.
5. R. W. K. Odoni, “On the norms of algebraic integers,” Mathematica,22, No. 1, 71–80 (1975).