SALOMAA, A. On color-families of graphs. Annales Fennici Mathematici, [S. l.], v. 6, n. 1, p. 135–148, 1981. DOI: 10.5186/aasfm.1981.0619. Disponível em: https://afm.journal.fi/article/view/134405. Acesso em: 14 apr. 2025.