1. The stoplight method: a qualitative approach for health literacy research;Hadden;HLRP: Health Literacy Research and Practice,2017
2. National Institutes of Health. Plain language: getting started or brushing up [Internet]. Bethesda, MD: National Institutes of Health, 2013 [cited May 31, 2017]. (http://www.nih.gov/clearcommunication/plainlanguage/gettingstarted/index.htm)
3. A new readability yardstick.
4. Fry’s readabilty graph: clarifications, validity, and extension to level 17;Fry;Journal of Reading,1977
5. SMOG grading: a new readability formula;McLaughlin;Journal of Reading,1969