Articles
http://www.bbc.com/future/story/20140606-why-we-must-save-dying-languages
http://www.wholeearth.com/issue/2100/article/138/disappearing.languages
https://www.nytimes.com/2007/09/18/world/18cnd-language.html
https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=7981&context=rtd
https://www.gla.ac.uk/media/media_141050_en.pdf
Other sources
The Cambridge Handbook of Endangered Languages edited by Peter K. Austin and Julia Sallabank
https://www.linguisticsociety.org/content/what-endangered-language
http://www.endangeredlanguages.com/
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