Degradation of humic acid in water by single- and dual-frequency ultrasound methods
ZHAO Li, YANG Yanling, LI Xing, ZHOU Zhiwei, ZHANG Yang, MA Changhong
CIESC Journal . 2014, (9): 3700 -3704 .  DOI: 10.3969/j.issn.0438-1157.2014.09.054