@article{DAN_1964_159_6_a2,
     author = {A. M. Il'in},
     title = {On a class of ultraparabolic equations},
     journal = {Doklady Akademii Nauk},
     pages = {1214--1217},
     publisher = {mathdoc},
     volume = {159},
     number = {6},
     year = {1964},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1964_159_6_a2/}
}