References
- Duke-Elder S: Textbook of Ophthalmology, vol IV. St. Louis, CV Mosby Co, 1949, p 3795.
- Kramer ME: Centropics. Am Orthopt J 12:132–147, 1962.
- MacLean F: Home orthoptics, its purpose, goals and limitations. Manuel Walter Reed Army Medical Center, 1967, pp 19–47.