%0 Journal Article
%A V. V. Golovchanskii
%A M. N. Smotrov
%T An explicit formula for the number of classes of primitive hyperbolic elements in the group $\Gamma_0(N)$
%J Sbornik. Mathematics
%D 2008
%P 1009-1031
%V 199
%N 7
%U http://geodesic.mathdoc.fr/item/SM_2008_199_7_a3/
%G en
%F SM_2008_199_7_a3