United Nations, 1999
Buku Teks
Sormin, Devina Ariany, author
Universitas Indonesia, 2017
UI - Skripsi (Membership)
Wilcox, Clair, author
Macmillan, 1949
Buku Teks
Viner, Jacob, author
George Allen and Unwin, 1960
Buku Teks
Lenway, Stefanie Ann
Pitman, 1985
Buku Teks