Gaya APA

Swanson, C, P. (NULL). Glolier academic encyclopedia jilid 20 W-X-Y-Z . USA:: USA: Grolier International; 1991.

Gaya MLA

Swanson, Carl, P.. "Glolier academic encyclopedia jilid 20 W-X-Y-Z". USA:: USA: Grolier International; 1991, NULL. Text.