1. Inaugural-Dissertation zur Erlangung der Doktorw�rde der Hohen Philophische Fakult�t der Georg-August-Universit�t zu G�ttingen, 1912.
2. Obituary Notices of Fellows of the Royal Society 1950-1951; VII: 183.
3. Uncrowned King. The Life of Prince Albert. The Free Press: New York, NY, 1997; 264.