On the zeta function of monodromy of a polynomial map A. Libgober; S. Sperber — 1995 Compositio Mathematica
Newton polyhedra and the degree of the L-function associated to an exponential sum. A. Adolphson; S. Sperber — 1987 Inventiones mathematicae
Logarithmic decay and overconvergence of the unit root and associated zeta functions B. Dwork; S. Sperber — 1991 Annales scientifiques de l'École Normale Supérieure