Gaya APA

Nault, William H., Groman, Jeff. (1992). The World Book Encyclopedia, Volume 21: W - X - Y - Z . London: World Book, Inc..

Gaya Chicago

Nault, William H., Groman, Jeff. The World Book Encyclopedia, Volume 21: W - X - Y - Z. London: World Book, Inc., 1992. Text.

Gaya MLA

Nault, William H., Groman, Jeff. The World Book Encyclopedia, Volume 21: W - X - Y - Z. London: World Book, Inc., 1992. Text.

Gaya Turabian

Nault, William H., Groman, Jeff. The World Book Encyclopedia, Volume 21: W - X - Y - Z. London: World Book, Inc., 1992. Print.