Qianqian Li and  Shaoquan Sun,  Intuitionistic Fuzzy Implicative Ideals with Thresholds (λ,μ) of BCI-Algebras.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    January 2013, vol. 83(11). 1617 - 1621
    [viewed 16 May 2022]. Available from: https://publications.waset.org/pdf/9997230.