@article{SM_1980_37_3_a1,
     author = {N. V. Grigorenko},
     title = {Two problems in the {Galois} theory of differential fields for the field of formal power series},
     journal = {Sbornik. Mathematics},
     pages = {327--335},
     publisher = {mathdoc},
     volume = {37},
     number = {3},
     year = {1980},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1980_37_3_a1/}
}