Cancela, Ángeles, Rocío Maceiras, Víctor Alfonsín, and Ángel Sanchez. “Transesterification of Waste Frying Oil under Ultrasonic Irradiation”. European Journal of Sustainable Development 4, no. 2 (June 2, 2015): 401. Accessed February 22, 2024. http://ojs.ecsdev.org/index.php/ejsd/article/view/274.