Shah N.A. and Anand N.S.,”Electronically tunable OTA based all pass circuit” Int. J. Electronics, Vol.68, pp.963-966(1990).
Chang C.M. and Chen P.C. , “Universal active filter with current gain using OTAs” International j. of Electronics” 71, pp.805-808(1991).
Sun Y. and Fidler J.K., “Novel OTA-C realization of biquadratic transfer function” Int. J. of Electronics, 75, pp.333-340(1993).