Some resources:
http://edition.cnn.com/2017/09/27/europe/catalan-referendum-explained/index.html
https://www.ft.com/content/138164a6-5b8a-11e7-b553-e2df1b0c3220
http://www.aljazeera.com/news/2017/09/catalonia-independence-referendum-170927083751915.html
