Newspaper Enterprise Association, 1985
Buku Referensi
edited by Jeffrey H. Hacker
Canada Grolier, 1986
Buku Teks
edited by John W. Wrigth
Penguin Group, 2003
Buku Referensi
editor in-chief, Seymour Kurtz
New York Times, c1969
Buku Referensi
planned and supervised by Dan Golenpaul Associates
McGraw-Hill, 1960
Buku Referensi