(1991). Grolier International encyclopedia. Grolier Incorporated.
Cita Chicago (17th ed.)Grolier International Encyclopedia. Danbury, Conn.: Grolier Incorporated, 1991.
Cita MLA (9th ed.)Grolier International Encyclopedia. Grolier Incorporated, 1991.
Atenció: Aquestes cites poden no estar 100% correctes.