Two applications of elementary knot theory to Lie algebras and Vassiliev invariants. Bar-Natan, Dror, Le, Thang T.Q., Thurston, Dylan P. (2003) Geometry & Topology
Two-fold branched coverings of S3 have type six. Maria Rita Casali (1992) Revista Matemática de la Universidad Complutense de Madrid In this work, we prove that every closed, orientable 3-manifold M3 which is a two-fold covering of S3 branched over a link, has type six.