Sandburg, Carl (1993). "Introduction". In Hendrik, George; Hendrik, Willene (eds.). Billy Sunday and Other Poems. Harcourt Brace & Company. pp. xi–xii.
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Van Wienen, Mark (March 1991). "Taming the Socialist: Carl Sandburg's Chicago Poems and its Critics". American Literature. 63 (1). Duke University Press: 89–103. doi:10.2307/2926563. JSTOR2926563., pp. 99–101.
jstor.org
Van Wienen, Mark (March 1991). "Taming the Socialist: Carl Sandburg's Chicago Poems and its Critics". American Literature. 63 (1). Duke University Press: 89–103. doi:10.2307/2926563. JSTOR2926563., pp. 99–101.
Monroe, Harriet (May 1916). "Chicago Granite:Chicago Poems by Carl Sandburg". Poetry. 8 (2): 90–93. JSTOR20570797.