@article{DAN_1970_190_2_a0,
     author = {M. I. Vishik and V. V. Grushin},
     title = {Elliptic boundary value problems that are degenerate on a submanifold of the boundary},
     journal = {Doklady Akademii Nauk},
     pages = {255--258},
     publisher = {mathdoc},
     volume = {190},
     number = {2},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_190_2_a0/}
}