https://cran.r-project.org/web/packages/Xplortext/index.html https://cran.r-project.org/web/packages/RcmdrPlugin.temis/index.html https://cran.r-project.org/web/packages/tm/ http://www.iramuteq.org/ https://cran.r-project.org/web/packages/FactoMineR/index.html