Each 11-vertex graph without 4-cliques has a triangle-free 2-partition of vertices. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 91, p. 127–147, 1999. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/275. Acesso em: 11 jan. 2026.