“…The growing number of studies on text complexity published worldwide, has not exhausted the topic even for the English language (Solnyshkina, Solovyev, Gafiyatova, Martynova, 2022) extent lexical density affects complexity of English academic texts thus testing the wellknown belief that lexical density predicts text complexity (Daller, Van Hout and Treffers-Daller, 2003) Guiraud's Index (Giroud, 1954), Corrected TTR (Carroll, 1964), Index of Herdan (Herdan, 1960, 1964), Maas (Maas, 1972, Tweedie and Baayen, 1998, Treffers-Daller, 2013; U Notational variant of Maas (Dugast, 1978;1979), D score (Malvern, Richards, 1997)…”