1 1 10 Z. Poeloengan Additional Author Pusat Penelitian Kelapa Sawit (PPKS) Additional Author Iman Yani Harahap Additional Author Fatmawati, Gale Ginting Additional Author Amir Purba, Suroso Rahutomo Additional Author Subronto, Dwi Asmono Additional Author Syamsul Anwar Additional Author P.L. Tobing, Z. Poeloengan Additional Author mixed material 08532141 Medan Pusat Penelitian Kelapa Sawit (PPKS) 2000 cover_warta_vol8no2.jpg