C ílin, Constantin. “On Totally Contact Umbilical Submanifolds of a Manifold With a Sasakian 3-Structure”. Rev. Téc. Fac. Ing. Univ. Zulia 27, no. 3 (1). Accessed October 31, 2025. https://produccioncientifica.luz.edu.ve/index.php/tecnica/article/view/5857.