H. Purnama Putra, B. Pandu Mursanto, and A. Handayani, “Utilization of Human Urine as Fertilizer with Magnesium Oxide (MgO), Zeolite and Activated Carbon as Absorbent”, Int. J. Adv. Sci. Eng. Inf. Technol., vol. 4, no. 3, pp. 173–176, Jun. 2014.