References
- Cuppers, Curt: Orthoptic and Pleoptic Problems in Germany, Parts I and II, Lectures given at Sheffield and Leeds, England, 1958.
- Kramer Mary Everist: Centroptics, Amer Orthopt J, 12:132–147, 1962.
- Linksz, Arthur: Theory of Pleoptics. In: Pleoptics. Int Ophthal Clin, 1 No. 4:747–785 (Dec.) 1961.