Ellis, Harry B.
World Pub., 1965
Buku Teks
Krause, Lawrence B.
Prentice-Hall, 1964
Buku Teks
Savage, Khatarine
Walck, 1969
Buku Teks
Sachs, Jeffrey D.
Penguin Press, 2008
Buku Teks
Deniau, Jena Francois
Frederick A. Praeger Publishers, 1960
Buku Teks