Prentice-Hall, 1967
Buku Teks SO
Pi, Ying-Hsien
World Anti-Communist League, 1986
Buku Teks
Garvy, George
Federal Reserve Bank of New York, 1966
Buku Teks SO
Sokolovsky, Joan
Westview Press, 1990
Buku Teks SO
Gyeszly, Suzanne D.
The Borgo Press, 1994
Buku Referensi