Abdel-Rahman, Zaid. “A Comparison Between the Product-Refill and the Equalization Oxygen Pressure Swing Adsorption Processes”. Iraqi Journal of Chemical and Petroleum Engineering 19, no. 1 (March 31, 2018): 61-66. Accessed November 27, 2019. http://ijcpe.uobaghdad.edu.iq/index.php/ijcpe/article/view/227.