VerĂ³nica Diaz Quezada,  Predominance of Teaching Models Used by Math Teachers in Secondary Education.   journal   = {International Journal of Educational and Pedagogical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    November 2018, vol. 144(12). 1649 - 1655
    [viewed 16 October 2019]. Available from: https://publications.waset.org/pdf/10009889.