{{Cite| last1 = Larmarange| first1 = Joseph| last2 = Ludecke| first2 = Daniel| last3 = Wickham| first3 = Hadley| last4 = Bojanowski| first4 = Michal| last5 = Briatte| first5 = François| title = labelled: Manipulating Labelled Data| access-date = 2021-12-21| date = 2021-10-29| url = https://CRAN.R-project.org/package=labelled}}