@article{RM_1961_16_5_a20,
     author = {B. P. Paneah},
     title = {A certain class of differential operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     year = {1961},
     volume = {16},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1961_16_5_a20/}
}