426 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1957 



ACKNOWLEDGMENT 



I feel particularly indebted to R. C. Fletcher and H. Boyet for their 

 many valnable comments and suggestions. 



REFERENCES 



1. D. Polder, Phil. Mag., 40, p. 99, Jan., 1949. 



2. H. Suhl and L. R. Walker, B.S.T.J., 33, 3, May, 1954. See Fig. 9g, p. 615, and 



Table I, p. 642. 



3. G. H. B. Thompson, Nature, 175, p. 1135, June 25, 1955. 



4. A. L. Mikaelyan. Dokladv, A. N. USSR, 98, 6, pp. 941-944, 1954. 



5. H. Seidel, Proc. I.R.E., 44, p. 1410, Oct., 1956. 



i 



