@article{IM_1993__112_3_144114,
     author = {Karsten Grove and Peter Petersen},
     title = {A radius sphere theorem.},
     journal = {Inventiones mathematicae},
     pages = {577--584},
     publisher = {mathdoc},
     volume = {112},
     number = {3},
     year = {1993},
     zbl = {0801.53029},
     url = {http://geodesic.mathdoc.fr/item/IM_1993__112_3_144114/}
}