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Credit
The detection of colour-blindness & imperfect eyesight by the methods of Dr. Snellen, Dr. Daae, and Prof. Holmgren : with a table of coloured Berlin wools and sheet of test-types / by Charles Roberts. Public Domain Mark. Source: Wellcome Collection.
Provider
This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.