Pangemanan S P, Hartono B, Devadoss S, Sondakh L W and Ali B 2014:  
Economic analysis of traditional duck farmer’s household in Minahasa Regency North Sulawesi, Indonesia. 
 Livestock Research for Rural Development. Volume 26, Article #136. 
 Retrieved 
, from http://www.lrrd.org/lrrd26/7/pang26136.html