Recommended reading:
Anderson K, Maclean J & Lynch T (2004) Study Speaking 2nd edition Cambridge: Cambridge University Press
Brazil D (1997) The Communicative Value of Intonation Cambridge: Cambridge University Press
Brown P & Levinson S.C. (1987) Politeness: Some Universals in Language Usage Cambridge: Cambridge University Press
Bygate M (1987) Speaking Oxford: Oxford University Press
Carter R & McCarthy M (1997) Exploring Spoken English Cambridge: Cambridge University Press
Kirkpatrick A (2007) World Englishes Implications for International Communication and English Language Teaching Cambridge: Cambridge University Press
Powell M (2002) Presenting in English Boston: Thomson Heinle
Rogerson P & Gilbert J.B. (1984) Speaking Clearly Cambridge: Cambridge University Press
Thorne S (2008) Mastering Advanced English Language Basingstoke: Palgrave Macmillan