@article{MAN_1971__195_162205,
     author = {M Sugimoto and K. Shiohama},
     title = {On the {Differentiable} {Pinching} {Problem.}},
     journal = {Mathematische Annalen},
     pages = {1--16},
     publisher = {mathdoc},
     volume = {195},
     year = {1971},
     zbl = {0218.53063},
     url = {http://geodesic.mathdoc.fr/item/MAN_1971__195_162205/}
}