COMBE, Ph.; NENCKA, H. Cooperative networks and frustration on graphs. Methods of Functional Analysis and Topology, [S. l.], v. 3, n. 4, p. 40–50, 1997. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/47. Acesso em: 19 dec. 2025.