Jian Tang,  On Weakly Prime and Weakly Quasi-Prime Fuzzy Left Ideals in Ordered Semigroups.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2012, vol. 68(8). 842 - 847
    [viewed 16 April 2024]. Available from: https://publications.waset.org/pdf/4224.