Munehiro Iwami,  Persistence of Termination for Term Rewriting Systems with Ordered Sorts.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    March 2007, vol. 3(3). 200 - 204
    [viewed 23 April 2024]. Available from: https://publications.waset.org/pdf/13396.