@article{DE_1976_12_6_a6,
     author = {E. L. Tonkov},
     title = {The linear problem on the optimal control of periodic solutions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1007--1011},
     publisher = {mathdoc},
     volume = {12},
     number = {6},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_6_a6/}
}