@article{DE_1973_9_8_a0,
     author = {V. G. Boltyanskii},
     title = {The support principle in optimal control problems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1363--1370},
     publisher = {mathdoc},
     volume = {9},
     number = {8},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_8_a0/}
}