https://forestdeclaration.org/images/uploads/resource/2019NYDFReport.pdf
https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.37.4.115
https://www.britishcouncil.org/sites/default/files/languages_for_the_future_2017.pdf
https://www.inequalityindex.com/