Nainggolan, Hotden, Johndikson Aritonang, Marlon Sihombing, Tavi Supriana, and Ma’ruf Tafsin. “Structural Modelling of Rice Fields-Buffalo Livestock Based Integrated Agricultural Systems in the Context of Regional Development in Humbang Hasundutan, Indonesia”. Future of Food: Journal on Food, Agriculture and Society 7, no. 2/3 (December 2, 2019): 106. Accessed December 8, 2019. http://futureoffoodjournal.org/index.php/FOFJ/article/view/251.