@article{MS_1990__180_4_a2,
     author = {{\CYRS}.{\CYRZ}. {\CYRL}{\cyre}{\cyrv}{\cyre}{\cyrn}{\cyrd}{\cyro}{\cyrr}{\cyrs}{\cyrk}{\cyri}{\cyrishrt}},
     title = {On types of degenerate elliptic operators},
     journal = {Matemati\v{c}eskij sbornik},
     pages = {513--528},
     publisher = {mathdoc},
     volume = {180},
     number = {4},
     year = {1990},
     zbl = {0698.35065},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MS_1990__180_4_a2/}
}