THE WORLD BOOK ENCYCLOPEDIA. (1989). The world book encyclopedia: U - V. World Book.
Chicago Style aipamenaTHE WORLD BOOK ENCYCLOPEDIA. The World Book Encyclopedia: U - V. Chicago: World Book, 1989.
MLA aipamenaTHE WORLD BOOK ENCYCLOPEDIA. The World Book Encyclopedia: U - V. World Book, 1989.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.