edited by Richard Mann
Gateway Books, 1995
Buku Teks
O`Neill, William L., author
Harper & Row Publishers, 1975
Buku Teks
Citra Media Persada, 1995
Buku Referensi
Citra Media Persada, 1995
Buku Referensi
Webster, J.B., author
Frederick A. Praeger, 1967
Buku Teks