[
Bybee, J. L. and S. Fleischman (eds). 1995. Modality in grammar and discourse. Amsterdam: John Benjamins, pp. 503-517.
]Search in Google Scholar
[
Council of Europe. Common European Framework of Reference. [online] Available: http://www.coe.int/t/dg4/linguistic/Source/Framework_EN.pdf [2011, September 6].
]Search in Google Scholar
[
Croft, W. and D.A. Cruse. 2004. Cognitive Linguistics. Cambridge: Cambridge University Press.10.1017/CBO9780511803864
]Search in Google Scholar
[
Dik, S. 1997. The Theory of Functional Grammar. Berlin, New York: Mouton de Gruyter.
]Search in Google Scholar
[
Groefsema, M. 1995. ‘Can, may, must and should: a Relevance Theoretic account’ in Journal of Linguistics 31, pp. 53-79.
]Search in Google Scholar
[
Haegeman, L. 1983. The semanitcs of ‘will’ in present-day British English: a unified account. Brussels: Paleis de Academiën.
]Search in Google Scholar
[
Halliday, M.A.K. and M.I.M. Matthiessen. 2004. An Introduction to Functional Grammar. London: Arnold.
]Search in Google Scholar
[
Huddleston, R. and G. Pullum. 2002. The Cambridge grammar of the English language. Cambridge: Cambridge University Press.10.1017/9781316423530
]Search in Google Scholar
[
Kay, S. and V. Jones. 2009. New Inside Out. Intermediate. Students’s Book. Oxford: Macmillan.
]Search in Google Scholar
[
Klinge, A. 1993. ‘The English modal auxiliaries: from lexical semantics to utterance interpretation’ in Journal ofLinguistics 29, pp. 315-357.
]Search in Google Scholar
[
Leech, G. 2004 (1971). Meaning and the English verb. London: Longman.
]Search in Google Scholar
[
Littlewood, W. 1991 (1981). Communicative Language Teaching. An introduction. Cambridge: Cambridge University Press.
]Search in Google Scholar
[
Lyons, J. 1977. Semantics. Cambridge: Cambridge University Press.
]Search in Google Scholar
[
Murphy, R. 1994 (1985). English Grammar in Use. A self-study reference and practice book for intermediatestudents. Cambridge: Cambridge University Press.
]Search in Google Scholar
[
Palmer, F. 1991 (1986). Mood and modality. Cambridge: Cambridge University Press.
]Search in Google Scholar
[
Papafragau, A. 2000. Modality: the issues in the semantics-pragmatic interface. Amsterdam: Elsevier Science.10.1163/9780585474199
]Search in Google Scholar
[
Richards, J.C. and T.S. Rodgers. 2001 (1986). Approaches and Methods in Language Teaching. Cambridge: Cambridge University Press.
]Search in Google Scholar
[
Soars L. and J. Soars. 2009. New Headway. Intermediate. Student’s book. Oxford: Oxford University Press.
]Search in Google Scholar
[
Westney, P. 1994. ‘Rules and pedagogical grammar’ in Perspectives on Pedagogical Grammar. T. Odlin (ed.) Cambridge: Cambridge University Press, pp. 72-96.
]Search in Google Scholar
