@article{GDZPPN002319446, title = {A Short Proof of the Rydakov-Safarevic Theorem.}, journal = {Mathematische Annalen}, volume = {250}, year = {1980}, pages = {171-174}, zbl = {0457.14018}, url = {http://dml.mathdoc.fr/item/GDZPPN002319446} }
Lang, William E.; Nygaard, Niels O. A Short Proof of the Rydakov-Safarevic Theorem.. Mathematische Annalen, Tome 250 (1980) pp. 171-174. http://gdmltest.u-ga.fr/item/GDZPPN002319446/