Partial fraction decompositions and expansions of zero
Joseph Lehner · Transactions of the American Mathematical Society · 1958
8) This holds under the more general condition that gk{z) is at most of the zero type of order 1, by Wigert's theorem.See beginning of §2.130 (3) Unpublished.The only published proof is in Petersson [2].(4) A discussion of other types of expansions of zero can be found in [6], (5) The factor cp(k) appears because each gk(n) occurs 0(£) times as h runs mod k, {h, k) =1.