Hukum perjanjian dalam Islam - Chairuman Pasaribu (Sinar Grafika, 1996)
ast c.1/oen, c.2/ir,c.3-5/ir,c.6-7/oen, c.8/ir,c.9/oen. c,10/ast c.11/ir,c.12/tr,c.13/ir,c.14/ir,c.15