Phung, Lan Huong, Trung Kien Tran, The Cuong Nguyen, Hong Quang Do, Thu Tra Phan, Hong Son Vu, and Tien Huy Nguyen. 2012. “Optimization Research into the Ultrasonic-Assisted Extraction to Separate Polyphenol from Green Tea Waste”. ASEAN Journal of Chemical Engineering 12 (2), 52-60. https://dev.journal.ugm.ac.id/v3/AJChE/article/view/8132.