Hanover Pub.,, 1981
Buku Referensi
Burnard, Philip
Chapman&Hall,, 1995
Buku Referensi
Susiana Nugraha
Universitas Indonesia, 2017
Artikel Jurnal
World Health Organization
World Health Organization, 1990
Buku Teks
Masriadi
Tamalatea school of health science, makassar, public health, department of epidemiology, 2016
Artikel Jurnal