@article{MZM_1981_30_2_a9,
     author = {M. M. Vinogradov},
     title = {Extensions of fields and extensions of linear differential operators},
     journal = {Matemati\v{c}eskie zametki},
     pages = {237--248},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1981_30_2_a9/}
}