@article{GDZPPN002220423, title = {Einstein Spaces Isometrically Diffeomorphic to a Sphere.}, journal = {Manuscripta mathematica}, volume = {22}, year = {1977}, pages = {1-6}, zbl = {0358.53030}, url = {http://dml.mathdoc.fr/item/GDZPPN002220423} }
Simon, Udo. Einstein Spaces Isometrically Diffeomorphic to a Sphere.. Manuscripta mathematica, Tome 22 (1977) pp. 1-6. http://gdmltest.u-ga.fr/item/GDZPPN002220423/