%0 Journal Article
%A Preiss, David
%T On the first derivative of real functions (Preliminary communication)
%J Commentationes Mathematicae Universitatis Carolinae
%D 1970
%P 817-822
%V 11
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMUC_1970__11_4_a12/
%G en
%F CMUC_1970__11_4_a12