1. W. Stewart Duke Elder: “Text Book of Ophthalmology”, Volume ii, page 1364.
2. Richard E. Scammon and Ellery N. Armstrong: “On the Growth of the Human Eyeball and Optic Nerve”. Journal of Comparative Neurology, Volume xxxviii, 1924–1925, page 165.
3. Daniel B. Kirby: “The Eye and its Diseases”, edited by C. Berens, 1936, page 577.
4. W. Stewart Duke Elder: Loco citato, page 1365.
5. P. A. Jaensch:“Anatomische Untersuchungen eines angeborenen Totalstars”, Archiv für Ophthalmologic, Volume cxv, 1924, page 81.