2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/63232We prove the rationality of the Kähler cone and the positivity of $c_2(X)$, if $X$ is a Calabi-Yau-threefold with $ρ(X)=2$ and has an embedding into a ${\bb P}^n$-bundle over ${\bb P}^m$ in the cases $(n,m)=(1,3),(3,1)$. The case $(n,m)=(2,2)$ has been done in the first part of this paper. Moreover, if $(n,m)=(3,1)$, we describe the 'other' contraction different from the projection.22 pagesAlgebraic Geometry14J32;14J30text