RT Journal Article SR Electronic T1 What matters, when, for whom? three questions to guide population health scholarship JF Injury Prevention JO Inj Prev FD BMJ Publishing Group Ltd SP injuryprev-2017-042415 DO 10.1136/injuryprev-2017-042415 A1 Sandro Galea A1 Katherine M Keyes YR 2017 UL http://injuryprevention.bmj.com/content/early/2017/10/07/injuryprev-2017-042415.abstract AB