RT Journal Article SR Electronic T1 The prevalence of vitamin D deficiency among female college students at Qatar University JF Saudi Medical Journal JO Saudi Med J FD Prince Sultan Military Medical City SP 964 OP 965 VO 32 IS 9 A1 Elham A. Sharif A1 Nasser M. Rizk YR 2011 UL http://smj.org.sa/content/32/9/964.abstract AB