“Studying the Factors Effect on the Flowability of (ZnO – CuO Al2O3) Catalyst With Blending of Different Lubricants through Hopper”.
Al-Khwarizmi Engineering Journal, vol. 5, no. 4, Dec. 2009, pp. 18-24,
https://alkej.uobaghdad.edu.iq/index.php/alkej/article/view/579.