Jarkani 2013. 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. 2, 2 (Dec. 2013), 44–48.