Kittipong Tripetch and  Nobuhiko Nakano,  CMOS Positive and Negative Resistors Based on Complementary Regulated Cascode Topology with Cross-Coupled Regulated Transistors.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2017, vol. 131(11). 1156 - 1162
    [viewed 25 February 2021]. Available from: https://publications.waset.org/pdf/10008536.