1. P. Lawaetz:Phys. Rev. B,1, 3460 (1971).
2. A detailed analysis of this argument can be found inA. C. Beer:Galvanomagnetic Effects in Semiconductors, edited byF. Seitz andD. Turnbull (New York, N. Y., and London, 1963);E. G. S. Paige:The electrical conductivity of germanium, inProgress in Semiconductors, Vol.8, edited byA. F. Gibson andR. E. Burgess (London, 1964),
3. R. A. Stradling andV. V. Zhukov:Proc. Phys. Soc.,87, 263 (1965).
4. M. Cardona, W. Paul andH. Brooks:Helv. Phys. Acta,33, 229 (1960).
5. A. H. Walton andP. L. Reimann:J. Phys. C,3, 1410 (1970).