@article{GDZPPN00209844X, title = {An Eigenvalue Pinching Theorem.}, journal = {Inventiones mathematicae}, volume = {69}, year = {1982}, pages = {253-256}, zbl = {0505.53018}, url = {http://dml.mathdoc.fr/item/GDZPPN00209844X} }
Croke, Christopher B. An Eigenvalue Pinching Theorem.. Inventiones mathematicae, Tome 69 (1982) pp. 253-256. http://gdmltest.u-ga.fr/item/GDZPPN00209844X/