Cita APA (7a ed.)
(1990). Year Book. The 1990 World Book: A Review of the Events of 1989.The Annual Supplement to The World Book Encyclopedia. The World Book,Inc.
Cita Chicago Style (17a ed.)
Year Book. The 1990 World Book: A Review of the Events of 1989.The Annual Supplement to The World Book Encyclopedia. Chicago: The World Book,Inc, 1990.
Cita MLA (9a ed.)
Year Book. The 1990 World Book: A Review of the Events of 1989.The Annual Supplement to The World Book Encyclopedia. The World Book,Inc, 1990.
Precaución: Estas citas no son 100% exactas.