R. Herdiansah and A. P. Lontoh, “Manajemen Pemupukan Tanaman Kelapa Sawit (Elaeis guineensis Jacq.) di Kebun Rambutan Sumatera Utara”, Bul. Agrohorti, vol. 6, no. 2, pp. 296–304, May 2018, doi: 10.29244/agrob.v6i2.22529.