Cita APA (7th ed.)
World Book, Inc. (2004). The World Book Encyclopedia: Volume -21. World Book, Inc.
Cita Chicago (17th ed.)
World Book, Inc. The World Book Encyclopedia: Volume -21. Chicago: World Book, Inc, 2004.
Cita MLA (9th ed.)
World Book, Inc. The World Book Encyclopedia: Volume -21. World Book, Inc, 2004.
Atenció: Aquestes cites poden no estar 100% correctes.