@article{ZNSL_1980_103_a20,
     author = {V. M. Tsvetkov},
     title = {Examples of extensions with {Demushkin's} group},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {146--149},
     publisher = {mathdoc},
     volume = {103},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1980_103_a20/}
}