@article{oai:tsukuba.repo.nii.ac.jp:00016291,
 author = {Zheng, Yongfan},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jun},
 pages = {135--143},
 title = {On isometry of a complete Riemannian manifold to a sphere},
 volume = {18},
 year = {1994}
}