GUTIN, G.; KOH, K. M.; TAY, E. G.; YEO, A. On the Number of Quasi-Kernels in Digraphs. BRICS Report Series, [S. l.], v. 8, n. 7, 2001. DOI: 10.7146/brics.v8i7.20461. Disponível em: https://tidsskrift.dk/brics/article/view/20461. Acesso em: 27 apr. 2024.