Arif, M. S., Er-chuan, Z. and Hua-fei, S. (2015) “JACOBI FIELDS ON THE MANIFOLD OF FREUND”, Italian Journal of Pure and Applied Mathematics, 34, pp. 181–188. Available at: https://journals.uniurb.it/index.php/ijpam/article/view/6343 (Accessed: 7 August 2026).