IskandarI., and IrwantiI. “Use of Volcanic Sand As a Natural Fertilizer: Increasing Release of NutrientsUse of Volcanic Sand As a Natural Fertilizer: Increasing Release of Nutrients”. Jurnal Ilmu Tanah Dan Lingkungan, Vol. 5, no. 1, Apr. 2003, pp. 23-28, doi:10.29244/jitl.5.1.23-28.