APA استشهاد

(1970). 1971 Britannica yearbooks of science and the future. Encyclopaedia Britannica.

استشهاد بنمط شيكاغو

1971 Britannica Yearbooks of Science and the Future. Chicago: Encyclopaedia Britannica, 1970.

MLA استشهاد

1971 Britannica Yearbooks of Science and the Future. Encyclopaedia Britannica, 1970.