%0 Journal Article
%A A. A. Agrachev
%A R. V. Gamkrelidze
%T The index of extremality and quasiextremal controls
%J Doklady Akademii Nauk
%D 1985
%P 777-781
%V 284
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1985_284_4_a0/
%G ru
%F DAN_1985_284_4_a0