Surtinah, Surtinah. 2009. “PEMBERIAN PUPUK ORGANIK SUPER NATURAL NUTRITION (SNN) PADA TANAMAN SELADA (Lactuca Sativa, L) DI TANAH ULTISOL”. Jurnal Ilmiah Pertanian 6 (1), 20-25. https://doi.org/10.31849/jip.v6i1.1291.