1. Frost Robert. The Figure a Poem Makes from Collected Poems of Robert Frost. New York: Holt, Rinehart, and Winston, 1939.
2. Warren Austin. Theory of Literature, Harcourt, Brace and Company 1948.
3. Lynen. F. John. The Pastoral Art of Robert Frost. (New Haven Yale University Press, 1967.
4. Brooks Cleanth. Modern Poetry and Tradition, The University of North Carolina Press 1939.
5. The Poems of Robert Frost, New York, Modern Library, Edition, 1949.