Donoghue, Denis. "The Golden Key."

The New York Review of Books (December 21, 1967): 34-36. Donoghue offers thought-provoking, though speculative, discussions on MacDonald's use of metaphor, nature, and adolescence.

Hein, Rolland. The Harmony Within: The Spiritual Vision of George MacDonald.

Grand Rapids, MI: Christian University Press, n.d. Hein discusses "The Golden Key" at the end of chapter 7.

His focus is on the theme of "the upward mobility of life."

Lewis, C. S. "Preface." In George MacDonald: An Anthology. New York: Macmillan, 1947. Lewis characterizes the type of fantasy MacDonald wrote.

MacDonald, Greville. George MacDonald and His Wife. New York: Dial Press, 1924. This is the standard edition of MacDonald's life and letters.

Manlove, C. N. Modern Fantasy: Five Studies. Cambridge: Cambridge University Press, 1975. Manlove discusses symbolism in "The Golden Key" and shows how the arousal of a desire for heaven is the active ingredient in MacDonald's fantasy...