Fortune
McGraw-Hill, 1956
Buku Teks
Ferre, John P., author
Charles E. Merrill Pub. Co., 1983
Buku Referensi
Churchill Livingstone, 2003
Buku Teks
Swales, John M., author
Cambridge University Press, 2004
Buku Teks
Wilson, Bright E., Jr.
Dover Publications, 1990
Buku Teks