%0 Journal Article %A V. G. Boltyanskii %T The method of local cross sections in the theory of optimal processes %J Differencialʹnye uravneniâ %D 1968 %P 2166-2183 %V 4 %N 12 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1968_4_12_a2/ %G ru %F DE_1968_4_12_a2