Nguyen Hieu Phuong and Nguyen Quang Thieu 2012 The effect of chicken, cow and pig manure on Phyllanthus amarus yield and its natural compounds.  Proceedings of the International Conference "Livestock-Based Farming Systems, Renewable  Resources and the Environment", 6-9 June 2012, Dalat, Vietnam (Editors: Reg Preston and Sisomphone Southavong) http:/www.mekarn.org/workshops/dalat2012/html/phuong.nlu2.htm