. 2014 Feb 22;11:22. doi: 10.1186/1479-5868-11-22
Copyright © 2014 Mehtälä et al.; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
Figure 2.
Flow diagram of article selection.