@article{DE_1978_14_9_a26,
     author = {E. L. Tonkov},
     title = {A remark on the controllability of a linear periodic system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1715--1717},
     publisher = {mathdoc},
     volume = {14},
     number = {9},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_9_a26/}
}