Bui Xuan Men and Tran Thi Thuy Hang  2012 Use of Tra fish by-products and water hyacinth as replacements for protein, minerals and vitamins in diets of laying ducks raised in a biosecure duck-fish system on smallholdings in the Mekong Delta. 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/bxmen.ctu2.htm