M Kasi, Pashtoon I Gilani, Ahmed Ahmad, Khabir Z Janjua, Naveed WHO Simplified Grading System: A Guide for the Assessment of Trachoma <p>(Photos: from [<a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0010044#pmed-0010044-b11" target="_blank">11</a>], with permission from WHO)</p> simplified;grading 2013-02-22
    https://plos.figshare.com/articles/figure/_WHO_Simplified_Grading_System_A_Guide_for_the_Assessment_of_Trachoma_/633115
10.1371/journal.pmed.0010044.g003