Pehlivani, K., A. Elshani, and X. Lajqi. “The Role of Oxygen Concentration of 8 and 10 Mg/L in the Main Fermentation of Beer”. ANGLISTICUM. Journal of the Association-Institute for English Language and American Studies, vol. 4, no. 1, Dec. 2015, pp. 109-12, https://anglisticum.org.mk/index.php/IJLLIS/article/view/232.