STERNAGEL, C. Certified Kruskal’s Tree Theorem. Journal of Formalized Reasoning, [S. l.], v. 7, n. 1, p. 45–62, 2014. DOI: 10.6092/issn.1972-5787/4213. Disponível em: https://jfr.unibo.it/article/view/4213. Acesso em: 8 feb. 2023.