The new encyclopedia Brittanica in 30 volumes.

MLA

Mortimer, J.A. The New Encyclopedia Brittanica In 30 Volumes. Fifteenth edition Chicago: Encyclopædia Britannica, 1975.

APA

Mortimer, J. (1975). The new encyclopedia Brittanica in 30 volumes. Fifteenth edition Chicago: Encyclopædia Britannica.

Chicago

Mortimer, J.A. The New Encyclopedia Brittanica In 30 Volumes. Fifteenth edition Chicago: Encyclopædia Britannica, 1975.