Belkhelfa, M., and F. Mahi. “Second Order Parallel Tensors on $S$ -Manifolds and Semi-Parallel Hypersurfaces of $S$ -Space Forms”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 10 (February 9, 2026): 1422–1429. Accessed February 16, 2026. https://umj.imath.kiev.ua/index.php/umj/article/view/1524.