CHRISTENSEN, P. A. Hyper-AFLs and ET0L Systems. DAIMI Report Series, [S. l.], v. 3, n. 35, 1974. DOI: 10.7146/dpb.v3i35.6456. Disponível em: https://tidsskrift.dk/daimipb/article/view/6456. Acesso em: 9 may. 2024.