Dursun, U., and N. C. Turgay. 2019. “Space-Like Surfaces in Minkowski Space $E^4_1$ With Pointwise 1-Type Gauss Map”. Ukrains’kyi Matematychnyi Zhurnal 71 (1), 59-72. https://umj.imath.kiev.ua/index.php/umj/article/view/1419.