Mohamed N. Ali, Hanan A. Fouad, Ashraf M. Hennigal, Ahmed E. Naguib. “Yeast Waste Water Treatment Using Fixed Biofilm Reactor Packed With Hybrid Bio-Carrier”. Design Engineering, Sept. 2021, pp. 12182 -93, http://www.thedesignengineering.com/index.php/DE/article/view/4373.