Ewald Hering's (1899) On the Limits of Visual Acuity: A Translation and Commentary: With a Supplement on Alfred Volkmann's (1863) Physiological Investigations in the Field of Optics.

Ewald Hering's (1899) On the Limits of Visual Acuity: A Translation and Commentary: With a Supplement on Alfred Volkmann's (1863) Physiological Investigations in the Field of Optics.