ŞAHIN, T.; YILMAZ, M. On singularities of the Galilean spherical darboux ruled surface of a space curve in $G_3$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 10, p. 1377–1387, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2962. Acesso em: 5 dec. 2025.