1. in: Surface Science - Recent Progress and Perspectives, Chap. 7, Ed. and , CRC Press Inc., Cleveland 1974.
2. and , in: Structure and Bonding, Springer-Verlag Berlin/Heidelberg/New York 1979 (p. 41).
3. and , Electronic Processes in Ionic Crystals, Clarendon Press, Oxford 1952 (p. 168).
4. Proc. Conf. Static Electrification, Inst. Phys. Conf. Ser. No. 4, 1967 (p. 29).