Estimating the optimal model for the crude oil production chain of the Organization of Crude Oil Exporting Countries (OPEC) for the period (2005-2010). cbej [Internet]. 2022 Dec. 18 [cited 2024 Jul. 2];19(80):63-79. Available from: https://cbej.uomustansiriyah.edu.iq/index.php/cbej/article/view/7885