References
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- Fry Glenn A.: Handbook of Physiology. Section I: Neurophysiology. Washington. D.C., American Physiology Society, 1959, vol. I. pp. 647–670.
- Helmholtz, H.: Handbuch der Physiologischen Optik, ed. 3, Hamburg, Leopold Voss, 1909.
- Landolt, Edmund: Graefe Handbuch Augenheilk, 1904, vol. 4, pp. 122–127.
- Schapero, Max; Cline, David, and Hofstetter, Henry William: Dictionary of Visual Science, ed. 1, Philadelphia, Chilton, 1960.