1. Elschnig, A.: in Schwarz, O. (ed.): Encyclopaedic der Augenheilkunde. Leipzig, E. C. W. Vogel, 1904, p. 292. (Subsequently cited in Bothman L.: Suggestions for accurate records in ophthalmology, Elschnig's classification of normal disks. In Bothman, L. (ed.): Yearbook of Eye Ear Nose and Throat. Chicago, The Yearbook Publishers, 1947, p. 7.)
2. Kronfeld, P.: The early ophthalmoscopic diagnosis of glaucoma. New Eng. J. Opt. 3:163, 1952.
3. Chandler, P. A., and Grant, W. M.: Lectures on Glaucoma. Philadelphia, Lea and Febiger, 1965, pp. 14, 112.
4. Kronfeld, P.: The optic nerve. In Armaly, M. (ed.): Symposium on Glaucoma. Transactions of the New Orleans Academy of Ophthalmology. St. Louis, C. V. Mosby, 1967, p. 62.
5. Begg, I. S., Drance, S. M., and Goldman, H.: Fluorescein angiography in the evaluation of focal circulatory ischaemia of the optic nervehead in relation to the arcuate scotoma in glaucoma. Canad. J. Ophth. 7:68, 1972.