-, -.
(2011).
 Industrial & Operations Research Engineering (IND).
<em>Philippine Engineering Journal, 24</em>(2).
Retrieved from <a href="https://www.journals.upd.edu.ph/index.php/pej/article/view/2500" target="_new">https://www.journals.upd.edu.ph/index.php/pej/article/view/2500</a>