... regular covering ofG is a product of weighted L -functions of G. We are interested in factorizing the weightedzeta function of an irregular covering of a graph by its weighted L -functions. In this ... A. A. Terras, Zeta functions of finite graphs and coverings, part III,to appear in Adv. Math.[17] T. Sunada, L -Functions in Geometry and Some Applications, in ”Lecture Notes in Math.”, Vol. 1201, ... be any intermediate covering to H/G such that (K, ˜wK) is balanced. Then Kis a covering of G2, and so is an intermediate covering to H/G2.Conversely, let K be an intermediate covering to...