Gray, R. J. (1990). American poetry of the twentieth century. Longman.
芝加哥风格引文Gray, Richard J. American Poetry of the Twentieth Century. London: Longman, 1990.
MLA引文Gray, Richard J. American Poetry of the Twentieth Century. Longman, 1990.
警告：这些引文格式不一定是100％准确.