Nguyen Van Hung, Preston T R and Nguyen Tat Canh 2010 Amendment of sandy soil with composts made from animal excreta subjected to the traditional method or by enhancement with earthworms or a microbial inoculum.  International Conference on Livestock, Climate Change and Resource Depletion (Editor: Reg Preston),  Champasack University, Pakse, LAO PDR, 9-11 November 2010.  httm://www.mekarn.org/workshops/pakse/html/hung.hua.htm