Macmillan, Fiona
Aweet & Maxwell, 2001
Buku Teks SO
edited by Tensie Whelan; foreword by Peter A. A. Berle
New York : Uslan Press, 1991,
Buku Referensi
United Nations, 1999
Buku Teks SO
Riyanto
Universitas Indonesia, 2005
Buku Teks SO
Ketrin Triwidiastuty
Universitas Indonesia, 2005
UI - Skripsi Membership