Noersidiq, Azhary, et al. “Effect of Saccharomyces Cerevisiae and Cobalt in Ammoniated Oil Palm Trunk to In-Vitro Digestibility of Dry Matter, Organic Matter and Crude Protein”. Jurnal Biologi Tropis, vol. 23, no. 2, Mar. 2023, pp. 121-5, doi:10.29303/jbt.v23i2.4739.