Robert Tua Siregar, Hery Pandapotan Silitonga2. “Development Of Wastewater Treatment (IPAL) Communal Plant In Village Pardomuan Nauli In The District Laguboti District Toba Samosir With The Power Of Community Participation”. International Journal of Advanced Science and Technology, Vol. 29, no. 06, May 2020, pp. 5672 -80, http://sersc.org/journals/index.php/IJAST/article/view/19841.