TAFAMEL, Andrew Ehiabhi, and Onutomaha Dennis Akrawah. “Cost Efficiency of the Oil and Gas Industry in Nigeria: Data Envelopment Analysis”. Archives of Business Research 3, no. 6 (December 28, 2015). Accessed February 4, 2026. http://116.203.177.230/index.php/ABR/article/view/1656.