@article{DAN_1972_204_5_a2,
     author = {S. G. Gindikin},
     title = {Differential operators with real characteristics of high order},
     journal = {Doklady Akademii Nauk},
     pages = {1037--1040},
     publisher = {mathdoc},
     volume = {204},
     number = {5},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_204_5_a2/}
}