11 Koh V, Yang A, Saw SM, Chan YH, Lin ST, Tan MM, Tey F, Nah G, Ikram MK. Differences in prevalence of refractive errors in young Asian males in Singapore between 1996-1997 and 2009-2010. Ophthalmic Epidemiol. 2014 Aug;21(4):247-55.

11 Koh V, Yang A, Saw SM, Chan YH, Lin ST, Tan MM, Tey F, Nah G, Ikram MK. Differences in prevalence of refractive errors in young Asian males in Singapore between 1996-1997 and 2009-2010. Ophthalmic Epidemiol. 2014 Aug;21(4):247-55.