%0 Journal Article
%A Y. Ershov
%A M. Fried
%T Frattini Covers and Projective Groups Without the Extension Property.
%J Mathematische Annalen
%D 1980
%P 233-240
%V 253
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MAN_1980__253_163479/
%F MAN_1980__253_163479