Cita APA (7th ed.)

THE WORLD BOOK.. (2007). The world book U-V volume 20. World Book.

Cita Chicago (17th ed.)

THE WORLD BOOK.. The World Book U-V Volume 20. Chicago: World Book, 2007.

Cita MLA (9th ed.)

THE WORLD BOOK.. The World Book U-V Volume 20. World Book, 2007.