SANTOCANALE, L. The Alternation Hierarchy for the Theory of mu-lattices. BRICS Report Series, [S. l.], v. 7, n. 29, 2000. DOI: 10.7146/brics.v7i29.20163. Disponível em: https://tidsskrift.dk/brics/article/view/20163. Acesso em: 7 jul. 2022.