%0 Journal Article
%A G. I. Trushin
%T Third order conjugate systems and the problem of their focal transformations
%J Doklady Akademii Nauk
%D 1960
%P 265-268
%V 131
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1960_131_2_a12/
%G ru
%F DAN_1960_131_2_a12