@article{MM2_1977__22_154475,
     author = {Udo Simon},
     title = {Einstein {Spaces} {Isometrically} {Diffeomorphic} to a {Sphere.}},
     journal = {Manuscripta mathematica},
     pages = {1--6},
     publisher = {mathdoc},
     volume = {22},
     year = {1977},
     zbl = {0358.53030},
     url = {http://geodesic.mathdoc.fr/item/MM2_1977__22_154475/}
}