Esmaeili, B., Haghighatdoost, G., & Pashaie, F. (2022). On the r-Stablity Index of r-Maximal Closed Hypersurfaces in de Sitter Spaces: . Tamkang Journal of Mathematics, 53(2), 163–173. https://doi.org/10.5556/j.tkjm.53.2022.3639