Variations of Hodge structures of Calabi-Yau threefolds are special instance special Kaehler geometry. In this lecture, we review the relation between the two formulations. This allows us to explicitly compute the BCOV propagators in the holomorphic limit in terms of solutions to linear holomorphic PDE known as Picard-Fuchs equation. We give an overview of how to determine the F_g in this way for a hypersurfaces in a toric variety with two moduli and low g.