Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 38 2 2012 07 15 Optimal order finite element approximation for a hyperbolic‎ ‎integro-differential equation447 459 en Fardin Saedpanah University of Kurdistan, Department of Mathematics 2010 10 26 finite element method wave equation ‎ ‎integro-differential equation stability a priori error estimate