Hasantash, Gholam Hossein, Hamidreza Mostafaei, and Shaghayegh Kordnoori. 2012. “Modelling the Errors of EIA’s Oil Prices and Production Forecasts by the Grey Markov Model”. International Journal of Economics and Financial Issues 2 (3):312-19. https://mail.econjournals.com/index.php/ijefi/article/view/212.