SakharovaЕ., and YampolskyA. “Powers of the Curvature Operator of Space Forms and Geodesics of the Tangent Bundle”. Ukrains’kyi Matematychnyi Zhurnal 56, no. 9 (September 25, 2004): 1231-1243. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3837.