HANS, R. J. Maximal Covering Sets-II. The Journal of the Indian Mathematical Society, [S. l.], v. 35, n. 1-4, p. 181–203, 1971. DOI: 10.18311/jims/1971/16729. Disponível em: https://informaticsjournals.com/index.php/jims/article/view/16729. Acesso em: 8 may. 2024.