1. Ramon Y, Cajal S. Recollections of My Life. Santiago Ramon Y Cajal. Translated by EH Craigie from the third Spanish edition (1923). Philadelphia: American Philosophical Society; 1937; p. 564-5.
2. Hayreh SS. Blood supply of the optic nerve. In: Shaffer RN, Glaucoma Research Conference. Am J Ophthalmol. 1966;61:564.
3. Hayreh SS. Blood supply of the optic nerve head and its role in optic atrophy, glaucoma and oedema of the optic disc. Br J Ophthalmol. 1969;53:721–48.
4. Duke-Elder S, Wybar KC. System of Ophthalmology, Vol. 2: The anatomy of the visual system. London: Kimpton; 1961; p. 345,351, 358,69
5. Wedel C, Ruysch F. Epistola anatomica, problematica ad Fredericum Ruyschium. De oculorum tunicis. Amstelaedami: Janssonio-Waesbergios; 1737.