Cambridge University Press, 2009
eBooks
Lancers Publishing, 1983
Buku Teks
Robert Maynard Hutchins, editor in chief
Encyclopaedia Britannica, Inc., 1952
Buku Referensi
Mitsch, William J., author
John Wiley, 2007
Buku Teks
Schwartz, Robert, 1940-, author
Wiley Blackwell, 2015
Buku Teks