@article{SM_1973_20_3_a4,
     author = {A. V. Fursikov},
     title = {On~a~class of globally hypoelliptic operators},
     journal = {Sbornik. Mathematics},
     pages = {383--405},
     publisher = {mathdoc},
     volume = {20},
     number = {3},
     year = {1973},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1973_20_3_a4/}
}