A conditional symmetric memristive system with amplitude and frequency controlZhenyu Gu, Chunbiao Li, Xiaofang Pei, Changyuan Tao and Zuohua LiuEur. Phys. J. Special Topics, 229 6-7 (2020) 1007-1019DOI: https://doi.org/10.1140/epjst/e2020-900185-y