Tadic, V; Hamblion, EL; Keeley, S; Cumberland, P; Hundt, GL; Rahi, JS; (2010) 'Silent Voices' in Health Services Research: Ethnicity and Socioeconomic Variation in Participation in Studies of Quality of Life in Childhood Visual Disability. Investigative Ophthalmology & Visual Science , 51 (4) 1886 - 1890. 10.1167/iovs.09-4522. Green open access