. 2017 Dec 22;33(3):317–327. doi: 10.1093/heapol/czx180
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This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Figure 2.
Independent variables.