HEINS, M. Fundamental polygons of fuchsian and fuchsoid groups. Annales Fennici Mathematici, [S. l.], n. 337, 1964. DOI: 10.5186/aasfm.1964.337. Disponível em: https://afm.journal.fi/article/view/134039. Acesso em: 26 nov. 2024.