. 2012 Sep 27;12:159. doi: 10.1186/1471-244X-12-159
Copyright ©2012 Johnson 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 cited.
Figure 2.
Number and types ofexplanatory models over time.