Bibliografia

Principal

• Bourke, K. (2003) English verbs and tenses Bourke, K. (2003). English verbs and tenses. Oxford University Press.
• Vince, M. (2009) Macmillan English grammar in context - Intermediate Vince, M. (2009). Macmillan English grammar in context - intermediate. Macmillan education.  
• Lebeau, I., & Rees, G. (2014) New language leader-pre-intermediate coursebook Lebeau, I., & Rees, G. (2014). New language leader-pre-intermediate coursebook. Pearson.

Secundária

• Hornby, A.S. (2010) Oxford advanced learner's dictionary Hornby, A.S. (2010). Oxford advanced learner's dictionary. Oxford University Press.