Abdel-Sattar, Rashad Abdel-Baky, and Yasin Unluturk. “Normal Developable Surfaces of A Surface Along A Direction Curve”. Journal of the Indonesian Mathematical Society 26, no. 3 (November 5, 2020): 319–333. Accessed March 31, 2025. http://jims-a.org/index.php/jimsa/article/view/872.