alhatemy, mougd hadi, and mohammed hamed mahboba. “Improvement of Retread Blends Composed of Natural Rubber(Nr) And Polybutadiene Rubber(Br)”. Nahrain University College of Engineering Journal, vol. 11, no. 3, Mar. 2008, pp. 478-84, https://oldjournal.eng.nahrainuniv.edu.iq/index.php/main/article/view/545.