الجناني ع. ن., and الجابري ق. ع. ف. “Estimated Returns and Risks of Oil Prices Volatility in the International Market for the Period (1990 – 2017) ”. Journal of Petroleum Research and Studies, vol. 11, no. 2, June 2021, pp. 36-54, doi:10.52716/jprs.v11i2.502.