محمد يحيى م. Estimating simultaneous equations system of the world prices of the grains for the period (1961-2002). IQJOSS [Internet]. 2008 Dec. 1 [cited 2025 Sep. 10];8(2):205-22. Available from: https://edusj.uomosul.edu.iq/index.php/stats/article/view/29148