@article{MZ_1993__214_1_174566,
     author = {Greg\'orio Pacelli Bessa},
     title = {Differentiable sphere theorems for {Ricci} curvature.},
     journal = {Mathematische Zeitschrift},
     pages = {245--260},
     publisher = {mathdoc},
     volume = {214},
     number = {1},
     year = {1993},
     zbl = {0844.53028},
     url = {http://geodesic.mathdoc.fr/item/MZ_1993__214_1_174566/}
}