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@article{MAN_1980__253_163479, author = {Y. Ershov and M. Fried}, title = {Frattini {Covers} and {Projective} {Groups} {Without} the {Extension} {Property.}}, journal = {Mathematische Annalen}, pages = {233--240}, publisher = {mathdoc}, volume = {253}, year = {1980}, zbl = {0475.20021}, url = {http://geodesic.mathdoc.fr/item/MAN_1980__253_163479/} }
Y. Ershov; M. Fried. Frattini Covers and Projective Groups Without the Extension Property.. Mathematische Annalen, Tome 253 (1980), pp. 233-240. http://geodesic.mathdoc.fr/item/MAN_1980__253_163479/