T. Şahin and M. Yilmaz, “On singularities of the Galilean spherical darboux ruled surface of a space curve in $G_3$”, Ukr. Mat. Zhurn., vol. 62, no. 10, pp. 1377–1387, Oct. 2010, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2962