%0 Journal Article %A L. Anczyk %T On differentiable solutions of Böttcher's functional equation %J Annales Polonici Mathematici %D 1968 %P 217-221 %V 21 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/ap-21-2-217-221/ %R 10.4064/ap-21-2-217-221 %G en %F 10_4064_ap_21_2_217_221