@article{DE_1978_14_7_a6,
     author = {Ya. I. Rivkind},
     title = {A characteristic property of dynamical systems with a discrete spectrum},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1203--1207},
     publisher = {mathdoc},
     volume = {14},
     number = {7},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_7_a6/}
}