APA (7th ed.) Zitazioa

Scheel, R. L. (1987). Introduction to the future. ETC Publications.

Chicago Style (17th ed.) Zitazioa

Scheel, Randall L. Introduction to the Future. Palm Springs, Calif.: ETC Publications, 1987.

MLA (9th ed.) Zitazioa

Scheel, Randall L. Introduction to the Future. ETC Publications, 1987.