KOZEN, D.; PALSBERG, J.; SCHWARTZBACH, M. I. Efficient Recursive Subtyping. DAIMI Report Series, [S. l.], v. 21, n. 405, 1992. DOI: 10.7146/dpb.v21i405.6639. Disponível em: https://tidsskrift.dk/daimipb/article/view/6639. Acesso em: 8 may. 2024.