%0 Journal Article
%A K. Krzyżewski
%T On the approximate derivative of superposition
%J Commentationes Mathematicae
%D 1965
%P  123-127
%V 9
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.14708/cm.v9i2.5540/
%R 10.14708/cm.v9i2.5540
%G pl
%F 10_14708_cm_v9i2_5540