1. M.E. Van Valkenburg, Analog Filter Design (Holt, Rinehart, and Winston, 1982), pp. 223–256
2. W. Zemouri, E.A. Soliman, S.A. Mohmoud, High Frequency Tow-Thomas Tunable Filter Using OTA Based Voltage OP-AMP (International Symposium on Integrated Circuits, 2011), pp. 484–485
3. J.H. Huijsing, Operational Amplifiers (Kluwer Academic Publishers, 2001), pp. 350–352, 375–377