DE LLANO PAZ, Fernando. An evaluation of the energy and environmental policy efficiency of the EU member states in a 25-year period from a Modern Portfolio Theory perspective. International Journal of Sustainable Energy Planning and Management, Aalborg, Denmark, v. 26, p. 19–32, 2022. DOI: 10.5278/ijsepm.3482. Disponível em: https://journals.aau.dk/index.php/sepm/article/view/3482. Acesso em: 19 may. 2024.