Hjelm, John R., author
Jones & Bartlett Learning, 2010
Buku Teks
Nur Ulfah, author
Universitas Indonesia, 2019
Artikel Jurnal
Dini Hanifa, author
Fakultas Psikologi Universitas Indonesia, 2018
UI - Skripsi (Membership)
Alexander, Linda Lewis, author
Jones & Bartlett Learning, 2014
Buku Teks
World Health Organization
World Health Organization, 1981
Buku Teks