شريف, �.
(2003).
 نظـرية النظـم.
<em>Tafakkur, 5</em>(1).
Retrieved from <a href="http://journals.uofg.edu.sd/index.php/tfkr/article/view/584" target="_new">http://journals.uofg.edu.sd/index.php/tfkr/article/view/584</a>