@article{IM_1982__68_142934,
     author = {Christopher B. Croke},
     title = {An {Eigenvalue} {Pinching} {Theorem.}},
     journal = {Inventiones mathematicae},
     pages = {253--256},
     publisher = {mathdoc},
     volume = {68},
     year = {1982},
     zbl = {0505.53018},
     url = {http://geodesic.mathdoc.fr/item/IM_1982__68_142934/}
}