RT Journal Article SR Electronic T1 Pragmatism versus purity: effectiveness of the key informant methodology in a developing rural setting JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 989 OP 989 DO 10.1136/bjo.2006.111229 VO 91 IS 8 A1 Williams, C A1 Sparrow, J M YR 2007 UL http://bjo.bmj.com/content/91/8/989.1.abstract AB