%0 Journal Article
%A Cohen, Jeffrey
%T On non-Hurwitz groups and non-congruence subgroups of the modular group
%J Glasgow mathematical journal
%D 1981
%P 1-7
%V 22
%N 1
%U http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004419/
%R 10.1017/S0017089500004419
%F 10_1017_S0017089500004419