OKE, David Mautin; KAREEM, Salami Dada. An Inter-temporal Analysis of Operational Efficiency of Oil Firms: Further Evidence from Nigeria. International Journal of Energy Economics and Policy, [S. l.], v. 3, n. 2, p. 178–184, 2013. Disponível em: https://mail.econjournals.com/index.php/ijeep/article/view/421. Acesso em: 23 dec. 2024.