Yunusa, N., I. T. Idris, A. G. Zango, and M. U. Kibiya. “Gas Flaring Effects and Revenue Made from Crude Oil in Nigeria”. International Journal of Energy Economics and Policy, vol. 6, no. 3, July 2016, pp. 617-20, https://www.econjournals.com/index.php/ijeep/article/view/2761.