http://en.wikipedia.org/wiki/Semantic_change

http://www.sociolinguistics.uottawa.ca/shanapoplack/francais/pubs/articles/PoplackWalkerMalcolmson2006.pdf

http://biblioteca.uqroo.mx/hemeroteca/tesol_quartely/1967_2002_fulltext/Vol_28_3.pdf#page=116

http://www.robarts.yorku.ca/projects/lectures/pdf/rl_mcroberts.pdf