@incollection{AST_1984__119-120__267_0,
     author = {Sperber, Steven},
     title = {Newton polygons for general hyperkloosterman sums},
     booktitle = {Cohomologie $p$-adique},
     series = {Ast\'erisque},
     pages = {267--330},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {119-120},
     year = {1984},
     mrnumber = {773095},
     zbl = {0582.14005},
     language = {en},
     url = {http://www.numdam.org/item/AST_1984__119-120__267_0/}
}