Cangül, İ. N. And Yılmaz Özgür, N. 2004. On the Principal Congruence Subgroups of the Hecke-Group H( ), . Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry , vol.45 , 75-85.

Cangül, İ. N., & Yılmaz Özgür, N., (2004). On the Principal Congruence Subgroups of the Hecke-Group H( ), . Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry , vol.45, 75-85.

Cangül, İSMAİL, And Nihal Yılmaz Özgür. "On the Principal Congruence Subgroups of the Hecke-Group H( ), ," Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry , vol.45, 75-85, 2004

Cangül, İSMAİL N. And Yılmaz Özgür, Nihal Y. . "On the Principal Congruence Subgroups of the Hecke-Group H( ), ." Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry , vol.45, pp.75-85, 2004

Cangül, İ. N. And Yılmaz Özgür, N. (2004) . "On the Principal Congruence Subgroups of the Hecke-Group H( ), ." Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry , vol.45, pp.75-85.

@article{article, author={İSMAİL NACİ CANGÜL And author={Nihal Yılmaz Özgür}, title={On the Principal Congruence Subgroups of the Hecke-Group H( ), }, journal={Beitrage zur Algebra und Geometrie: Contributions to Algebra and Geometry }, year=2004, pages={75-85} }