Nazari S, Rostamy-Malkhalifeh M, Hamzehee A. An investigation of the undesirable outputs congestion in data envelopment analysis. Nexo Revista Científica [Internet]. 2020 Dec. 31 [cited 2025 Dec. 5];33(02):468-75. Available from: https://www.camjol.info/index.php/NEXO/article/view/10785