M. Rodionov and  Z. Dedovets,  Motivational Orientation of the Methodical System of Teaching Mathematics in Secondary Schools.   journal   = {International Journal of Educational and Pedagogical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    April 2019, vol. 149(5). 614 - 621
    [viewed 19 November 2019]. Available from: https://publications.waset.org/pdf/10010360.