Crawford, John
Aslib, 2000
Buku Teks SO
Pantry, Sheila
Facet Publishing, 2005
Buku Teks SO
Jessy Mahanani Utami
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 2017
UI - Skripsi Membership
Ray, Colin
UNESCO, 1979
Buku Teks SO
O`Brein, James M.
[Publisher not identified], [Date of publication not identified]
Artikel Jurnal