@article{JRAM_1985__360_152743,
     author = {A. Fr\"ohlich},
     title = {Orthogonal representations of {Galois} groups, {Stiefel-Whitney} classes and {Hasse-Witt} invariants.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {84--123},
     publisher = {mathdoc},
     volume = {360},
     year = {1985},
     zbl = {0556.12005},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1985__360_152743/}
}