1. Jr, J. B., Lea. S. G.: An Integrated Approach for the Development of Communication Skills. Interact Found, 1–16 (2009)
2. Hinkel. E.: Integrating the four skills: Current and historical perspectives. In: Kaplan. R. B. (ed.) Oxford Handbook in Applied Linguistics, pp. 110–126, Oxford University Press (2010)
3. Ellis, R.: Task-based language learning and teaching. Oxford University Press (2003)
4. Richards. J. C., Rodgers. T.: Approaches and methods in language teaching. Cambridge University Press (2001)
5. Richards. J. C., Schmidt. R.: Longman dictionary of language teaching and applied linguistics. Pearson Education Limited (2002)