Scheel, R. L. (1987). Introduction to the future. ETC Publications.
芝加哥风格引文Scheel, Randall L. Introduction to the Future. Palm Springs, Calif.: ETC Publications, 1987.
MLA引文Scheel, Randall L. Introduction to the Future. ETC Publications, 1987.
警告：这些引文格式不一定是100％准确.