1. Van Ruyven, L.J.: ‘Germanium-gallium phosphide heterojunctions’, September, 1964, Thesis, Technische Hogeschool Te Eindhoven, Netherlands
2. Donnelly, J.P.: ‘Studies of Ge-GaAs and Ge-Si heterojunctions’, September, 1965, Ph.D. Thesis, Carnegie Institute of Technology, Pittsburgh, Pa.