O dea, Thomas F.
Prentice-Hall, 1973
Buku Teks
Staiger, Ralph C., author
UNESCO, 1979
Buku Teks
edited by Gareth Williams, Martin Kenyon and Lynn Williams
Overseas Student Trust, 1987
Buku Referensi
Ira Hermosa, author
2002
UI - Skripsi (Membership)
Teddy Indira Budiwan, author
Universitas Indonesia, 2002
UI - Skripsi (Membership)