Widayat, W., Aulia, H. N., Hadiyanto, H. and Sasongko, S. B. (2015) “Kinetic Study on Ultrasound Assisted Biodiesel Production from Waste Cooking Oil”, Journal of Engineering and Technological Sciences, 47(4), pp. 374-388. doi: 10.5614/j.eng.technol.sci.2015.47.4.3.