Emerson, Ralph Waldo. “The Poet.” Essays: Second Series. 1844
https://www.poetryfoundation.org/articles/69389/from-the-poet
Emerson , Ralph Waldo. The Works of Ralph Waldo Emerson, vol. 9 (Poems) [1909]. http://oll.libertyfund.org/titles/emerson-the-works-of-ralph-waldo-emerson-vol-9-poems
Hallen, Cynthia, ed. Emily Dickinson Lexicon. Provo, Utah: Brigham Young University, http://edl.byu.edu/index.php, 2007.
Keller, Karl. The Only Kangaroo Among the Beauty. Emily Dickinson and America. Baltimore: Johns Hopkins University Press, 1979.
Miller, Cristanne. “Immediate U.S. Literary Predecessors.” Emily Dickinson in Context. Ed. Eliza Richards. New York: Cambridge University Press, 2013: 119-128, 121.