Gardner, W. H., Gerard Manley Hopkins (1844–1889): A Study of Poetic Idiosyncrasy in Relation to Poetic Tradition, Vol. 2, Oxford University Press, 1949, pp. 21, 22, 367.

Heller, Kevin, “Hopkins’s ‘Pied Beauty,’” in Explicator, Vol. 59, No. 4, Summer 2001, p. 192.

Hopkins, Gerard Manley, “Author’s Preface,” in Gerard Manley Hopkins: The Major Works, edited by Catherine Phillips, Oxford University Press, 1986, p. 106.

———, “God’s Grandeur,” in Gerard Manley Hopkins: The Major Works, edited by Catherine Phillips, Oxford University Press, 1986, p. 128.

———, Letter to Robert Bridges, August 21, 1877, in Gerard Manley Hopkins: The Major Works, edited by Catherine Phillips, Oxford University Press, 1986, p. 229.

———, Letter to Robert Bridges, April 2, 1878, in Gerard Manley Hopkins: The Major Works, edited by Catherine Phillips, Oxford University Press, 1986, pp. 228, 229.

———, Letter to Robert Bridges, February 15, 1879, in Gerard Manley Hopkins: The Major Works...