1. T. D. Schlabach,Bell Laboratories Record October (1972) p. 283.
2. C. B. Reed, ?Fuels, Minerals and Human Survival?, Ann Arbor Science Publishers, Ann Arbor, Michigan, USA (1975) p. 168.
3. A. Charkey and G. A. Dalin,Proc. 20th Annual Power Sources Conf. The PSC Publications Committee, Red Bank, New Jersey, USA (1966) p. 79.
4. C. E. Kent and W. N. Carson, Jr.,ibid (1966) p. 76.
5. C. E. Kent,Proc. 21st Annual Power Sources Conf. The PSC Publications Committee, Red Bank, New Jersey, USA (1967) p. 106.