@article{DE_1994_30_2_a4,
     author = {R. R. Gadyl'shin},
     title = {A two-dimensional analogue of the {Helmholtz} resonator with ideally rigid walls},
     journal = {Differencialʹnye uravneni\^a},
     pages = {221--229},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {1994},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1994_30_2_a4/}
}