1. Miniature Four-Dot Test
2. Orthoptics—Theory and Practice
3. Ogle KN: Optics. Springfield, Ill, Charles C Thomas, 1961, pp 162–163.
4. Duke-Elder S, Wybar KC: System of Ophthalmology, vol II, The Anatomy of the Visual System. St. Louis, CV Mosby Co, 1961, p 269.