Karacan, Murat Kemal, Dae Won Yoon, and Sezai Kiziltug. “Helicoidal Surfaces in the Three Dimensional Simply Isotropic Space I₃¹”. Tamkang Journal of Mathematics 48, no. 2 (June 30, 2017): 123-134. Accessed September 19, 2021. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/2200.