IONESCU, M.; KUMJIAN, A.; RENAULT, J. N.; SIMS, A.; WILLIAMS, D. P. Pushouts of extensions of groupoids by bundles of abelian groups. New Zealand Journal of Mathematics, [S. l.], v. 52, p. 561–581, 2021. DOI: 10.53733/136. Disponível em: https://nzjmath.org/index.php/NZJMATH/article/view/136. Acesso em: 27 apr. 2024.