1372 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1954 



13. J. R. Pierce, J. App. Phys., 25, pp. 179-183, Feb. 1954. 



14. Ping King Tien, Lester M. Field and D. A. Watkins, Proc. I.R.E., 39, p. 194, 



1951. 



15. Ping King Tien and Lester M. Field, Proc. I.R.E., 40, pp. 688-695, 1952. 



16. R. Kompfner, Rep. Progress. Phys., 15, pp. 275-327, 1952. 



17. C. C. Cutler and C. F. Quate, Phys. Rev., 80, pp; 875-878, 1950. 



18. J. R. Pierce, J. App. Phys., 8, pp. 93-933, 1954. 



19. D. A. Watkins, Proc. I.R.E., 40, pp. 65-70, 1952. 



20. R. W. Peter, R.C.A. Review, 13, pp. 344-368, 1952. 



21. C. F. Quate, paper presented at the Institute of Radio Engineers Electron 



Devices Conference, University of New Hampshire, 1952. 



