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. 2016 Nov 1;60:10.3402/fnr.v60.32613. doi: 10.3402/fnr.v60.32613

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© 2016 Mohsen Mazidi et al.

This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.

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Fig. 4 — Funnel plots detailing publication bias in the studies selected for analysis. Open circles represent observed published studies; open diamond represents observed effect size.