Mann, Thomas, "Introduction," in Demian, by Hermann Hesse, Harper & Row Publishers, 1965, pp. ix-x. Mileck, Joseph, "Hermann Hesse," in Dictionary of Literary Biography, Vol. 66: German Fiction Writers, 1885-1913, edited by James Hardin, Gale Research, 1988, pp. 180-224.

—, Hermann Hesse: Life and Art, University of California Press, 1978, p. 99.

Otten, Anna, ed., Hesse Companion, University of New Mexico Press, 1977, p. xii.