1. Hirschberg. Geschichte der Augenheilkunde in Gräfe-Sämisch's Handbuch der Augenheilkunde, 2nd Ed., Bd. xiii, S. 294–310.
2. System of Compleat Optics;Smaith;Cambridge,1738
3. Young, Thomas. Philosophical Trans. for 1801. Misc. Works of the Late Thomas Young. Ed. by George Peacock, London, 1855. Vol. 1, p. 49.
4. On the Anomalies of Accommodation of the Eye;Donders;Trans. by W. D. Moore, London,1864
5. A Manual of Examination of the Eyes;Landolt;Trans. by Swan M. Burnett, Philadelphia,1879