APA Style

Britannica, E. (1975). The New Encyclopaedia Britannica: Macropaedia Volume 19 (15th edition). Chicago: Encyclopaedia Britannica, Inc.

MLA Style

Britannica, Encyclopedia. "The New Encyclopaedia Britannica: Macropaedia Volume 19". 15th edition Chicago: Encyclopaedia Britannica, Inc, 1975. Text.