Editorial. REVISTA DE INVESTIGACIÓN SIGMA, [S. l.], v. 4, n. 01, 2017. DOI: 10.24133/sigma.v4i01.1142. Disponível em: https://journal.espe.edu.ec/ojs/index.php/Sigma/article/view/2%20-%203. Acesso em: 4 apr. 2025.