C.R., Lumbansiantar, N. W. T. Inggriati, & I G. Suarta. " THE LEVEL OF MOTIVATION OF FARMERS IN INTENSIVE PIG BREEDING (Case Study in Sipinggan Lumbansiantar Village Nainggolan District Samosir Regency North Sumatra Province)." Jurnal Peternakan Tropika [Online], 12.4 (2024): 458- 481. Web. 8 Apr. 2026