Mahdiyeh Abbasi and  Akbar Golchin,  Characterization of Monoids by a Generalization of Flatness Property.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    September 2015, vol. 106(10). 623 - 626
    [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/10002719.