21.Daum KM, Clore KA, Simms SS, et al. Productivity associated with visual status of computer users. Optometry. 2004 Jan;75(1):33-47.

21.Daum KM, Clore KA, Simms SS, et al. Productivity associated with visual status of computer users. Optometry. 2004 Jan;75(1):33-47.