Compensating your sales force : how to use commissions, draws, bonuses and quotas to keep your sales team hungry and productive / W. G. Ryckman & Robert G. Head. Ryckman, W. G. Head, Robert G. jt. aut. Labor economics 331.216 RYC Includes index. Chicago, Illinois : Probus, 1993. 1993. 1993 Text xiv, 238 p. ; eng