@article{SM_1999_190_3_a0,
     author = {A. G. Baskakov},
     title = {On correct linear differential operators},
     journal = {Sbornik. Mathematics},
     pages = {323--348},
     publisher = {mathdoc},
     volume = {190},
     number = {3},
     year = {1999},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1999_190_3_a0/}
}