Encyclopedia Britannica, Inc. (1990). Britannica book of the year 1990. Encyclopedia Brittanica, Inc.
Cita Chicago (17th ed.)Encyclopedia Britannica, Inc. Britannica Book of the Year 1990. Chicago: Encyclopedia Brittanica, Inc, 1990.
Cita MLA (9th ed.)Encyclopedia Britannica, Inc. Britannica Book of the Year 1990. Encyclopedia Brittanica, Inc, 1990.
Atenció: Aquestes cites poden no estar 100% correctes.