1. Gergis I.S., Cheung J.T., Trinh T.N., Sovero E.A. and Kobrin P.H., Appl. Phys. Lett., 60 (16), p. 2026, April 1992
2. Ekholm E.B. and McNight S.W., IEEE Trans. Microwave Theory Tech., MTT-38, p. 387, April 1990
3. Tokumitsu Y.,Ishizaki M,Iwakuni M.,and Saito T.,IEEE Trans. Microwave Theory Tech., MTT-31, p. 121, Feb. 1983
4. Klein N., Muller G., Piel H., Roas B., Schultz L., Klein U., and Peiniger M., Appl. Phys. Lett., 54 (8), p. 257, Feb 1989
5. Derov J.S., Drehman A.J., Suscavage M.J., Andrews R.J., Cohen E., Ianno N., and Thompson D., IEEE Microwave Guidewave Lett., 2, p.452, Nov. 1992