1. Lancaster WB. Refraction correlated with optics and physiological optics and motility limited to heterophoria. Springfield, IL: Charles C Thomas; 1952. p. 102.
2. Bielschowsky A. Lectures on motor anomalies. Hannover, NH: Dartmouth College Publications; 1943/1956.
3. von Noorden GK, Campos EC. Chapter 4: Physiology of ocular movements. In: Binocular vision and ocular motility. 6th ed. St. Louis: Mosby; 2002. p. 71–6.
4. Lee SY, Koo NK. Change of stereoacuity with aging in normal eyes. Korean J Ophthalmol. 2005;19(2):136–9.
5. Bielschowsky A. Uber die ruhelage der Augen, vol 66. Bericht 39. Versammlung ophthalmologische Gesellschaft, Heidelberg. Wiesbaden, JF Bergmann, p. 67 ff; 1913.