Hidayat, F., M. Syarovy, I. Pradiko, and S. Rahutomo. “Application of Cow Manure to Improve Soil Chemical Characteristics and Promote Vegetative Growth of Oil Palm (Elaeis Guineensis Jacq.) Seedling on Sub Soil Media”. Jurnal Penelitian Kelapa Sawit, Vol. 28, no. 1, Apr. 2020, pp. 51-58, doi:10.22302/iopri.jur.jpks.v28i1.107.