@article{MZM_1967_1_6_a11,
     author = {V. G. Boltyanskii},
     title = {Non-oscillatory optimal systems of the second order},
     journal = {Matemati\v{c}eskie zametki},
     pages = {703--714},
     year = {1967},
     volume = {1},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1967_1_6_a11/}
}