Ballool، M. M.، و Steele، H. B. (1981). ECONOMIC ANALYSIS OF THE LONG-TERM PLANNING INVESTMENT STRATEGIES FOR THE OIL SURPLUS FUNDS IN SAUDI ARABIA An Optimal Control Approach (رسالة دكتوراه غير منشورة). University of Houston، هيوستن. مسترجع من http://search.mandumah.com/Record/619466
Ballool، Mukhtar Mohammad، و Henry B. Steele. "ECONOMIC ANALYSIS OF THE LONG-TERM PLANNING INVESTMENT STRATEGIES FOR THE OIL SURPLUS FUNDS IN SAUDI ARABIA An Optimal Control Approach" رسالة دكتوراه. University of Houston، هيوستن، 1981. مسترجع من http://search.mandumah.com/Record/619466