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Higgerson J, Halliday E, Ortiz-Nunez A, Brown R, Barr B.Higgerson J, et al. Among authors: barr b.J Epidemiol Community Health. 2018 Mar;72(3):252-258. doi: 10.1136/jech-2017-209882. Epub 2018 Jan 12.J Epidemiol Community Health. 2018.PMID: 29330166Free PMC article.
Daras K, Alexiou A, Rose TC, Buchan I, Taylor-Robinson D, Barr B.Daras K, et al. Among authors: barr b.J Epidemiol Community Health. 2021 Aug;75(8):729-734. doi: 10.1136/jech-2020-215227. Epub 2021 Feb 4.J Epidemiol Community Health. 2021.PMID: 33542030Free PMC article.