M. Tjioe, M.-J. Gerritsen, L. Juhlin, and P. C. van de Kerkhof, “Treatment of vitiligo vulgaris with narrow band UVB (311 nm) for one year and the effect of addition of folic acid and vitamin B12”, Acta Derm Venereol, vol. 82, no. 5, pp. 369–372, Nov. 2002.