%0 Journal Article
%A A. A. Agrachev
%A R. V. Gamkrelidze
%T A~second order optimality principle for a~time-optimal problem
%J Sbornik. Mathematics
%D 1976
%P 547-576
%V 29
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SM_1976_29_4_a6/
%G en
%F SM_1976_29_4_a6