SamokhvalovS. E. “Group-Theoretic Description of Riemannian Spaces”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 9 (September 25, 2003): 1238-1248. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3996.