Zahiripour, S. A., Jalali, A. A. (2012). Designing an Optimal Proportional-Integral Sliding Surface for a Quarter Car Active Suspension System with Suspension Components Possessing Uncertain Constants and Nonlinear Characteristics. *Nashriyyah -i Muhandisi -i Barq va Muhandisi -i Kampyutar -i Iran*, 10(3), 113-118.