“…Text Complexity Estimation: While for Dale and Chall (1949) the notion of text readability involved "the extent to which they [readers] understand it [the text], read it at an optimal speed, and find it interesting", 3 most classical (Flesch, 1948;Gunning, 1952;Kincaid et al, 1975;McLaughlin, 1969) and modern (Sheehan et al, 2014;Flor and Beigman Klebanov, 2014;Vajjala and Meurers, 2012;Schwarm and Ostendorf, 2005) measures of text readability/complexity focus on reading comprehension, including special formulas and models designed for special populations, such as young children (Spache, 1953), learners of English as a second language (Beinborn et al, 2014;Heilman et al, 2007), adults with mental disabilities (Feng et al, 2009), among others.…”