%0 Journal Article
%A P. P. Kasyankov
%T The conditions for the existence of a stigmatic image in electron optical systems having a curvilinear axis
%J Doklady Akademii Nauk
%D 1958
%P 497-500
%V 120
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1958_120_3_a15/
%G ru
%F DAN_1958_120_3_a15