Technical Efficiency of Coal Mines: A Stochastic Frontier and Data Envelopment Analysis for Eastern Salt Range of Punjab. Journal of Asian Development Studies, [S. l.], v. 9, n. 3, p. 17–25, 2020. DOI: 10.62345/jads.2020.9.3.2925. Disponível em: https://poverty.com.pk/index.php/Journal/article/view/2925. Acesso em: 30 jul. 2026.