Khamaruddin, Salbiah, Lestari Rahmah, and Tri Prasetyorini. “The Relationship of House Environmental Sanitation With Infection of Muhamadiyah Elementry School Students in Deli Serdang District”. Asian Journal of Applied Sciences 7, no. 6 (December 25, 2019). Accessed July 25, 2021. https://ajouronline.com/index.php/AJAS/article/view/6022.