KörpinarT., and DemirkolR. C. “Curvature and Torsion Dependent Energy of Elastica and Nonelastica for a Lightlike Curve in the Minkowski Space”. Ukrains’kyi Matematychnyi Zhurnal 72, no. 8 (August 18, 2020): 1095-1105. Accessed September 25, 2020. http://umj.imath.kiev.ua/index.php/umj/article/view/847.