edited by Christian Schittich
Edition Detail, 2002
Buku Teks
Bahamon, Alejandro, author
Page One Pub, 2004
Buku Referensi
Washington, D.C. International Cooperation Administration 1960,
Buku Teks
Ronny Amir, author
Universitas Indonesia, 1987
UI - Skripsi Membership
Grant-Hays, Brenda, author
McGraw-hill, 2003
Buku Teks