@article{MAN_1991__290_4_164833,
     author = {Gerhard van der Geer},
     title = {Kloosterman sums and the p-torsion of certain {Jacobians.}},
     journal = {Mathematische Annalen},
     pages = {549--564},
     year = {1991},
     volume = {290},
     number = {4},
     zbl = {0731.14014},
     url = {http://geodesic.mathdoc.fr/item/MAN_1991__290_4_164833/}
}