@article{DVMG_2009_9_1_a5,
     author = {V. V. Golovchanskii and M. N. Smotrov},
     title = {Multiplicative characteristics of function for  the number of classes of primitive hyperbolic elements in the group $\Gamma_0(N)$ by level~$N$},
     journal = {Dalʹnevosto\v{c}nyj matemati\v{c}eskij \v{z}urnal},
     pages = {48--73},
     publisher = {mathdoc},
     volume = {9},
     number = {1},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DVMG_2009_9_1_a5/}
}