@article{DAN_1969_189_1_a2,
     author = {M. I. Vishik and V. V. Grushin},
     title = {Elliptic pseudodifferential operators on a closed manifold which are degenerate on a submanifold},
     journal = {Doklady Akademii Nauk},
     pages = {16--19},
     publisher = {mathdoc},
     volume = {189},
     number = {1},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_189_1_a2/}
}