“PHENOLOGICAL OBSERVATION ON EIGHT OIL PALM (Elaeis Guineensis Jacq.) VARIETIES USING THERMAL UNIT CONCEPT”. Jurnal Penelitian Kelapa Sawit, vol. 27, no. 1, Apr. 2019, pp. 57-69, https://doi.org/10.22302/iopri.jur.jpks.v27i1.71.