1. BARRETT , J. F. , and COALES , J. F. , 1955 ,Proc. Instn elect. Engrs, 103C , 190 .
2. BARKER , H. A. , and OBIDEOWU , S. N. , 1973 ,Proc. Instn elect. Engrs, 120 , 1293 .
3. BARKER , H. A. , and PRADISTHAYON , T. , 1970 ,Proc. Instn elect. Engrs, 117 , 1857 .
4. BILLINGS , S. A. , and FAKHOTJRI , S. Y. , 1977 ,Electron. Lett. 13 , 502 ; 1978 a, I.E.E. Colloquium, Nonlinear System Ident., Digest No. 1978/31 ; 1978 b, Proc. Instn elect. Engrs, 125, 691 ; 1978 c, Ibid., 125, 1051 ; 1978 d, Ibid., 125,1307 ; 1979 a, Int. J. Systems Sci., 10,567 ; 1979 b, Proc. Instn elect. Engrs, 126,1013 ; 1979 c, Proceedings of the 17th I.E.E.E. Conference on Decision and Control, San Diego .
5. BRIGGS , P. A. N. , and GODFREY , K. R. , 1966 ,Proc. Instn elect. Engrs, 113 , 1259 .