BRADFIELD, J. C.; STEVENS, P. Observational Mu-Calculus. BRICS Report Series, [S. l.], v. 6, n. 5, 1999. DOI: 10.7146/brics.v6i5.20062. Disponível em: https://tidsskrift.dk/brics/article/view/20062. Acesso em: 23 apr. 2024.