. 2012 May 22;2(2):73–81. doi: 10.1016/j.jegh.2012.03.001
© 2012 Published by Elsevier Ltd. on behalf of Ministry of Health, Saudi Arabia.
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)