Mohamed, I. S., H. M. Khttab, S. K. Elsayed, M. G. El-Noby, and S. G. Elrammah. “A New Progressive and Efficient Royalty Model for Upstream Petroleum Industry”. International Journal of Energy Economics and Policy, vol. 12, no. 3, May 2022, pp. 287-9, doi:10.32479/ijeep.13153.