@article{DAN_1965_163_2_a0,
     author = {I. V. Gel'man},
     title = {On stable solvable extensions of partial differential operators},
     journal = {Doklady Akademii Nauk},
     pages = {279--281},
     publisher = {mathdoc},
     volume = {163},
     number = {2},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1965_163_2_a0/}
}