RT Journal Article SR Electronic T1 Review: vitamin D plus calcium, but not vitamin D alone, prevents osteoporotic fractures in older people JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 13 OP 13 DO 10.1136/ebm.11.1.13 VO 11 IS 1 YR 2006 UL http://ebm.bmj.com/content/11/1/13.abstract AB