APA

,, . (1991). The new encyclopaedia britannica, 1991: Annual. Chicago: Encyclopaedia Britannica Inc.

Chicago

,, . 1991. The new encyclopaedia britannica, 1991: Annual. Chicago: Encyclopaedia Britannica Inc.

Harvard

,, . (1991). The new encyclopaedia britannica, 1991: Annual. Chicago: Encyclopaedia Britannica Inc.

MLA

,, . The new encyclopaedia britannica, 1991: Annual. Chicago: Encyclopaedia Britannica Inc. 1991.