@article{DE_1982_18_8_a8,
     author = {V. M. Frolov},
     title = {The width of the $n$th zone of instability of {Mathieu's} equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1363--1368},
     publisher = {mathdoc},
     volume = {18},
     number = {8},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1982_18_8_a8/}
}