Sasongko, Mega Nur, and Widya Wijayanti. 2021. “Experiment Investigation on the Effect of Oxygen Percentage on Combustion Characteristics of Waste Cooking Oil Biodiesel”. International Journal of Integrated Engineering 13 (1): 39-45. https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/5554.