Cita APA

Hoffman, M. S. E. (1991). The world almanac and book of facts 1991.

Citación estilo Chicago

Hoffman, Mark S; Ed. The World Almanac and Book of Facts 1991. New York, World Almanac, 1991.

Cita MLA

Hoffman, Mark S; Ed. The World Almanac and Book of Facts 1991. 1991.