Pratama, H. S., W. P. Lokapirnasari, S. Soeharsono, M. A. Al-Arif, N. Harijani, and S. Hidanah. “Effect of Probiotics Bacillus Subtilis on Feed Efficiency and Egg Mass of Laying Hens”. Jurnal Medik Veteriner, vol. 4, no. 1, Apr. 2021, pp. 37-41, doi:10.20473/jmv.vol4.iss1.2021.37-41.