Dario Ramirez de Leon and  Oscar Chavez Bosquez and  Julian J. Francisco Leon,  Verification and Validation for Java Classes using Design by Contract. The Modular External Approach.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2012, vol. 64(4). 432 - 439
    [viewed 20 April 2024]. Available from: https://publications.waset.org/pdf/6862.