Cangül, İ. N. 1997. About some Normal Subgroups of Hecke Groups. Tr. J of Mathematics , vol.21 , 143-151.

Cangül, İ. N., (1997). About some Normal Subgroups of Hecke Groups. Tr. J of Mathematics , vol.21, 143-151.

Cangül, İSMAİL. "About some Normal Subgroups of Hecke Groups," Tr. J of Mathematics , vol.21, 143-151, 1997

Cangül, İSMAİL N. . "About some Normal Subgroups of Hecke Groups." Tr. J of Mathematics , vol.21, pp.143-151, 1997

Cangül, İ. N. (1997) . "About some Normal Subgroups of Hecke Groups." Tr. J of Mathematics , vol.21, pp.143-151.

@article{article, author={İSMAİL NACİ CANGÜL}, title={About some Normal Subgroups of Hecke Groups}, journal={Tr. J of Mathematics}, year=1997, pages={143-151} }