00325nam a2200109Ia 4500082002000000100002100020245011200041260003100153300002100184500000500205700000500210  a515.35bG618.ID  aGoldberg, Samuel  aIntroduction to difference equations; with illustrative examples from economics, psychology and sociologyb  aNew YorkbJohn Wileyc1958  axii, 260p. Index  a  a