@article{DE_1974_10_3_a19,
     author = {O. F. Mikulina},
     title = {Expansion in the eigenfunctions of a second order partial differential equation of polar type in the case of the whole plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {550--552},
     publisher = {mathdoc},
     volume = {10},
     number = {3},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1974_10_3_a19/}
}