  In this paper, following [6], we continue to develop the perturbing method of
constructing logarithmic series solutions to a regular A-hypergeometric system.
Fixing a fake exponent of an A-hypergeometric system, we consider some spaces
of linear partial differential operators with constant coefficients. Comparing
these spaces, we construct a fundamental system of series solutions with the
given exponent by the perturbing method. In addition, we give a sufficient
condition for a given fake exponent to be an exponent. As important examples of
the main results, we give fundamental systems of series solutions to
Aomoto-Gel'fand systems and to Lauricella's FC systems with special parameter
vectors, respectively.
