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