Open Access Maced J Med Sci. 2019 Jan 15; 7(1): 148–151. Arlinda Sari Wahyuni 1Department of Public Health and Community Medicine, Faculty of Medicine, Universitas Sumatera Utara, Padang Bulan, Medan Baru, Medan, Sumatera Utara 20155, Indonesia Ferdinan Benito Siahaan 1Department of Public Health and Community Medicine, Faculty of Medicine, Universitas […]