readability formulas - SERP Analysis

https://readabilityformulas.com/

https://readable.com/readability/readability-formulas/

https://en.wikipedia.org/wiki/Readability

https://www.ihs.gov/sites/healthcommunications/themes/responsive2017/display_objects/documents/Readability_Tools.pdf

https://www.litworks.org/post/readability-formulas-part-1-what-are-they-really-measuring

https://www.sciencedirect.com/science/article/pii/073839919190017Y

https://www.noslangues-ourlanguages.gc.ca/en/blogue-blog/readability-formulas-eng