Alvarez, H. T. (1990). Environmental crisis: Tomorrow may be too late. [publisher not identified].
芝加哥风格引文Alvarez, Heherson T. Environmental Crisis: Tomorrow May Be Too Late. [place of publication not identified]: [publisher not identified], 1990.
MLA引文Alvarez, Heherson T. Environmental Crisis: Tomorrow May Be Too Late. [publisher not identified], 1990.
警告：这些引文格式不一定是100％准确.