%0 Journal Article
%A V. M. Tsodyks
%T On sets of points where the derivative is $+\infty$ or $-\infty$ correspondingly
%J Doklady Akademii Nauk
%D 1957
%P 36-38
%V 113
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_113_1_a7/
%G ru
%F DAN_1957_113_1_a7