CALDAS, J. V. .; REBELO, J. . Technical efficiency and productivity growth in the farming system of the douro region: a stochastic frontier approach. Douro : Estudos & Documentos, [S. l.], n. 15, 2022. Disponível em: https://ojstest.xyz/ojsletras/index.php/dou/article/view/12642. Acesso em: 11 set. 2025.