  Chiral Perturbation Theory is a useful tool to aid in performing the various
extrapolations needed in lattice QCD calculations of physical quantities. These
include extrapolations in quark mass, finite lattice spacing and finite size of
the lattice. Especially the latter will become more important when the quark
masses on the lattice become smaller.
  Here we develop the needed two-loop integrals at finite volume to do the
calculations for masses and decay constants for all general mass cases.
  I will present results based on an expansion in Bessel functions as well as
on a version using theta functions and compare their efficiency. Work is in
progress to combine these results with two-loop ChPT calculations.
