On Harmonic Diffeomorphisms of the Unit Disc onto a Convex Domain

We prove a theorem for harmonic diffeomorphisms between the unit disc and a convex Jordan domain, which is a generalization of Heinz theorem E. Heinz (1959). On one-to-one harmonic mappings. Pacific J . Math ., 9 , 101-105] for harmonic diffeomorphisms of the unit disc onto itself. We give a number of corollaries of the theorem we prove.