Silaen, S. E., S. F. Ayu, and N. D. Hanafi. “Beef Cattle Breeder Income Improvement Strategy With Different Maintenance System in Langkat Regency”. Randwick International of Social Science Journal, Vol. 3, no. 4, Oct. 2022, pp. 878-90, doi:10.47175/rissj.v3i4.562.