Blau, Peter E. and Jon L. Lellenberg. "A Search for Emotional Peace." The Quest for Sir Arthur Conan Doyle: Thirteen Biographers in Search of a Life. Ed. Jon L. Lellenberg. Carbondale: Southern Illinois University Press, 1987. 146-158.

Cox, Don Richard. Arthur Conan Doyle. NY: Frederick Ungar Pub. Co., 1985. Introduction (11) and Chapter 6 (184-200).

Davies, Howard. "The Lost World: Conan Doyle and the Suspense of Evolution." Nineteenth-Century Suspense from Poe to Conan Doyle. Ed. Clive Bloom, Brian Docherty, Jane Gibb, and Keith Shand. NY: St. Martin's Press, 1988. 107-119.

Lamond, John. Arthur Conan Doyle: A Memoir. Port Washington, NY: Kennikat Press, 1972. Chapter 9 (110-112).

Malec, Andrew S. "Commitment to Great Causes." The Quest for Sir Arthur Conan Doyle: Thirteen Biographers in Search of a Life. Ed. Jon L. Lellenberg. Carbondale: Southern Illinois University Press, 1987. 64-76.

Nordon, Pierre. Conan Doyle: A Biography. NY: Holt, Rinehart and Winston, 1966. Chapter 19 concerns Professor Challenger (328-336).

Pearson, Hesketh. Conan Doyle. NY: Walker and Co., 1961. 217-221.