المصادر
https://en.wikipedia.org/wiki/Origin_...
https://www.britannica.com/topic/Afro...
http://linguistics.byu.edu/classes/Li...
http://www.hrpub.org/download/2014100...
https://en.wikipedia.org/wiki/Noam_Ch...
http://www.cog.brown.edu/people/liebe...
http://blogs.discovermagazine.com/dea...
https://mathildasanthropologyblog.wor...