1. Arditi A, Cagenello R. On the statistical reliability of letter-chart visual acuity measurements. Investig Ophthalmol Vis Sci. 1993;34(1):120–9.
2. Salmon JF. Kanski’s clinical ophthalmology - Ninth Edition. Edinburgh: Elsevier. 2020.
3. McGraw P, Winn B, Whitaker D. Reliability of the Snellen chart. BMJ. 1995;310:1481–2.
4. Colenbrander A. Measuring Vision and Vision Loss. Duane's Clinical Ophthalmology Volume 5, Chapter 51. Lippincott Williams & Wilkins. 2001.
5. Kaiser PK. Prospective evaluation of visual acuity assessment: a comparison of Snellen versus ETDRS charts in clinical practice (an AOS thesis). Trans Am Ophthalmol Soc. 2009;107:311–24.