@article{MAN_1990__288_1_164738,
     author = {John Douglas Moore},
     title = {On the number of minimal two-spheres of small area in manifolds with curvature bounded above.},
     journal = {Mathematische Annalen},
     pages = {323--344},
     publisher = {mathdoc},
     volume = {288},
     number = {1},
     year = {1990},
     zbl = {0694.53053},
     url = {http://geodesic.mathdoc.fr/item/MAN_1990__288_1_164738/}
}