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Austin N, Harper S, Strumpf E.Austin N, et al. Among authors: harper s.Epidemiology. 2016 Sep;27(5):682-9. doi: 10.1097/EDE.0000000000000505.Epidemiology. 2016.PMID: 27182641
Nandi A, Charters TJ, Strumpf EC, Heymann J, Harper S.Nandi A, et al. Among authors: harper s.J Epidemiol Community Health. 2013 Dec 1;67(12):1038-46. doi: 10.1136/jech-2012-202260. Epub 2013 Aug 22.J Epidemiol Community Health. 2013.PMID: 23969346
Nandi A, Hajizadeh M, Harper S, Koski A, Strumpf EC, Heymann J.Nandi A, et al. Among authors: harper s.PLoS Med. 2016 Mar 29;13(3):e1001985. doi: 10.1371/journal.pmed.1001985. eCollection 2016 Mar.PLoS Med. 2016.PMID: 27022926Free PMC article.