Al-Nasser , Abdul Rahman. “ A Comparative Study of the Level of Emotional Response and Self- Confidence Among Players and Teams the First and Last Centers in Iraq Super League Football”. Journal of Physical Education, vol. 22, no. 4, Dec. 2010, p. 23, https://jcope.uobaghdad.edu.iq/index.php/jcope/article/view/1621.