A graph-theoretical representation of PL-manifolds - A survey on crystallizations. M. Ferri; C. Gagliardi; L. Grasselli — 1986 Aequationes mathematicae
Heegaard and regular genus of 3-manifolds with boundary. P. Cristofori; C. Gagliardi; L. Grasselli — 1995 Revista Matemática de la Universidad Complutense de Madrid By means of branched coverings techniques, we prove that the Heegaard genus and the regular genus of an orientable 3-manifold with boundary coincide.