Saeid Haghjoo and  Ebrahim Reyhani and  Fahimeh Kolahdouz,  Evaluating the Understanding of the University Students (Basic Sciences and Engineering) about the Numerical Representation of the Average Rate of Change.   journal   = {International Journal of Educational and Pedagogical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    January 2020, vol. 158(2). 111 - 121
    [viewed 04 August 2020]. Available from: https://publications.waset.org/pdf/10011068.