A two-stage data envelopment analysis of efficiency of social-ecological systems: Inference from the sub-Saharan African countries ECOLOGICAL INDICATORS Journal Article Diogo Ferreira Publication Year of Publication: 2021 Identifiers Other Numbers: WOS:000615923500007 Locators URL https://doi.org/10.1016/J.ECOLIND.2021.107381 DOI: 10.1016/J.ECOLIND.2021.107381 Sustainable Development Goals