1. Irsch K, Guyton DL. Schematic drawing of the human eye. Eye features and anatomy. London: Springer-Verlag; 2014.
2. Levenson JH, Kozarsky A. Chapter 115: visual acuity. In: Clinical methods: the history, physical, and laboratory examinations. 3rd ed. Boston: Butterworth Publishers; 1990.
3. Spector RH. Chapter 58: the pupils. In: Clinical methods: the history, physical, and laboratory examinations. 3rd ed. Boston: Butterworth Publishing; 1990.
4. Al-Zubidi N, Khan R. Sixth nerve palsies. Springer-Verlag; 2018. p. 1642–6.
5. Gurney SP, Makanjuola T, Kutubi M, Parulekar M, Abbott J. How to use…the direct ophthalmoscope. Arch Dis Child Educ Pract Ed. 2017;103(2):102–9.