ÉSIK, Z.; KUICH, W. Rationally Additive Semirings. BRICS Report Series, [S. l.], v. 8, n. 42, 2001. DOI: 10.7146/brics.v8i42.21702. Disponível em: https://tidsskrift.dk/brics/article/view/21702. Acesso em: 1 may. 2024.