Jarkani, Akhmad Sopian, and Mahdalena. 2015. “Effect of Fertilizer and Fertilizer Manure Nickerson Star Swallow on Growth Seeds Rubber (Havea Brasiliensis Muell Arg) Origin Grafting: Pengaruh Pemberian Pupuk Nickerson Star Dan Pupuk Kotoran Burung Walet Terhadap Pertumbuhan Bibit Tanaman Karet (Havea Brasiliensis Muell Arg) Asal Okulasi”. Agrifarm: Jurnal Ilmu Pertanian 4 (2):44-48. https://journal.uwgm.ac.id/agrifarm/article/view/1328.