1Brooks, C. (ed.) Understanding Poetry: An Anthology for College Students [Z].New York: Holt, Rinehart and Winston, 1960.364-367.
2Warren R. Penn. The Themes of Robert Frost[ A]. In Cowden Roy. & Ann Arbor( eds. ). The Writer and His Craft [C]. University of Michigan Press, 1960. 218-233.
3Bronks, C. et al. (eds.) American Literatre: The Makers and the Making [Z]. New York: St. Martin' s Press, 1973. 1856-1865.
4Elliott, E. et al. Columbia Literary History of the United States [Z].(eds.)哥伦比亚美国文学史.李毅译.成都:四川辞书出版社,1994.781-789.
