@article{DAN_1984_276_4_a6,
     author = {V. P. Fedosov and N. N. Yanenko},
     title = {Equations with partial derivatives of half-integral degree},
     journal = {Doklady Akademii Nauk},
     pages = {804--808},
     year = {1984},
     volume = {276},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1984_276_4_a6/}
}