Roy, S., T. K. . Paul, S. . Maiti, and R. R. Pal. “Voltage Differencing Current Conveyor Based Voltage-Mode and Current-Mode Universal Biquad Filters With Electronic Tuning Facility”. International Journal of Engineering and Technology Innovation, vol. 11, no. 2, Apr. 2021, pp. 146-60, doi:10.46604/ijeti.2021.6821.