WASET
    Mehrnaz Najafi and  Hassan Haghighi,  Refinement of Object-Z Specifications Using Morgan-s Refinement Calculus.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2011, vol. 59(11). 1347 - 1356
    [viewed 10 May 2024]. Available from: https://publications.waset.org/pdf/2100.