SLATER, P. J. HOW PROVABLY GRACEFUL ARE THE TREES?. Journal of the Indonesian Mathematical Society, [S. l.], p. 133–136, 2012. DOI: 10.22342/jims.0.0.25.133-136. Disponível em: http://jims-a.org/index.php/jimsa/article/view/25. Acesso em: 2 may. 2024.