This article is unavailable. R. Withnall, J. Silver, G.R. Fern, A.L. Lipman, Experimental and theoretical luminous efficacies of phosphors used for producing white light from blue-emitting LEDs Digest of Technical Papers - SID International Symposium 38(1), pp. 515-518, 2007, ISSN 0007-966X. If you wish to obtain a copy please contact the author below: George.Fern@brunel.ac.uk