. 2011 Sep 2;31(14):1428–1438. doi: 10.1177/0333102411419681
© International Headache Society 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav
This article is distributed under the terms of the Creative Commons Attribution-Non Commercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page(http://www.uk.sagepub.com/aboutus/openaccess.htm).
Figure 1.
Study design.