On $K_{4}^{\prime}$-graphs. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 87, p. 271–277, 1995. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/420. Acesso em: 15 dec. 2025.