@article{ZNSL_1981_109_a1,
     author = {A. B. Venkov},
     title = {Automorphic scattering matrix for the {Hecke} group $\Gamma[2\cos(\pi/q)]$},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {34--40},
     publisher = {mathdoc},
     volume = {109},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1981_109_a1/}
}