@article{MZM_1975_17_1_a12,
     author = {N. V. Grigorenko},
     title = {Abelian extensions in {Picard--Vessiot} theory},
     journal = {Matemati\v{c}eskie zametki},
     pages = {113--117},
     publisher = {mathdoc},
     volume = {17},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1975_17_1_a12/}
}