DursunU., and TurgayN. C. “Space-Like Surfaces in Minkowski Space $E^4_1$ With Pointwise 1-Type Gauss Map”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 1 (January 25, 2019): 59-72. Accessed November 28, 2020. http://umj.imath.kiev.ua/index.php/umj/article/view/1419.