Biber, D., Johansson, S., Leech, G., Conrad, S. and Finegan, E. (1999) Longman Grammar
of Spoken and Written English. London: Longman.

Bybee, J. L. and Fleischman, S. (eds) (1995) Modality in Grammar and Discourse.
Amsterdam and Philadelphia: John Benjamins.

Bybee, J. L. (1995) ‘The semantic development of past tense modals in English.’ In: Bybee,
J. L. and Fleischman, S. (eds) Modality in Grammar and Discourse. Amsterdam and
Philadelphia: John Benjamins. 503-517.

Coates, J. (1983) The Semantics of the Modal Auxiliaries. London: Croom Helm.

Coates, J. (1995) ‘The expression of root and epistemic possibility in English.’ In: Bybee,
J. L. and Fleischman, S. (eds) Modality in Grammar and Discourse. Amsterdam and
Philadelphia: John Benjamins. 55-66.

Crompton, P. (1997) ‘Hedging in academic writing: Some theoretical problems.’ English
for Specifi c Purposes 16/4, 271-287. https://doi.org/10.1016/S0889-4906(97)00007-0

Dušková, L. (1972) ‘A contrastive study of can, may, must and their Czech equivalents.’
Studies in Modern Philology 1, 5-77.

Dušková, L. (1994) Mluvnice současné angličtiny na pozadí češtiny. Praha: Academia.

Facchinetti, R. (2003) ‘Pragmatic and sociological constraints on the functions of may in
contemporary British English.’ In: Facchinetti, R., Krug, M. and Palmer, F. R. (eds)
Modality in Contemporary English. Berlin: Mouton de Gruyter. 301-327.

Huddleston, R. (1993) Introduction to the Grammar of English. Cambridge: Cambridge
University Press.

Huddleston, R. and Pullum, G. (2002) The Cambridge Grammar of the English Language.
Cambridge: Cambridge University Press.

Hyland, K. (1995) ‘The author in the text: Hedging scientifi c writing.’ Hong Kong Papers
in Linguistics and Language Teaching 18, 33-42.

Hyland, K. (1998) Hedging in Scientifi c Research Articles. Amsterdam: John Benjamins.

Leech, G. (2003) ‘Modality on the move: The English modal auxiliaries 1961-1992.’ In:
Facchinetti, R., Krug, K. and Palmer, F. R. (eds) Modality in Contemporary English.
Berlin: Mouton de Gruyter. 223-240.

Leech, G. (2004) Meaning and the English Verb. London: Longman.

Leech, G. and Coates, J. (1980) ‘Semantic indeterminacy and the modals.’ In: Quirk,
R., Greenbaum, S., Leech, G. and Svartvik, J. (eds) Studies in English Linguistics.
London: Longman. 79-99.

Lyons, J. (1977) Semantics. Cambridge: Cambridge University Press.

Markkanen, R. and Schröder, H. (1997) ‘Hedging: A challenge for pragmatics and
discourse analysis.’ In: Markkanen, R. and Schröder, H. (eds) Hedging and Discourse:
Approaches to the Analysis of a Pragmatic Phenomenon in Academic Texts. Berlin
and New York: Walter de Gruyter. 3-20.

Palmer, F. R. (1990) Modality and the English Modals. London: Longman.

Papafragou, A. (2000) Modality: Issues in the Semantics-Pragmatics Interface. Oxford:
Elsevier.

Peters, P. (2004) The Cambridge Guide to English Usage. Cambridge: Cambridge
University Press.

Quirk, R., Greenbaum, S., Leech, G, and Svartvik, J. (1985) A Comprehensive Grammar
of the English Language. London: Longman.

Silva-Corvalán, C. (1995) ‘Interpretation of poder and deber.’ In: Bybee, J. L. and
Fleischman, S. (eds) Modality in Grammar and Discourse. Amsterdam and
Philadelphia: John Benjamins. 67-105.

Tárnyiková, J. (1978) ‘Semantic components of some modal verbs.’ Germanica
Olomucensia 4, 7-22.

Tárnyiková, J. (1985) Modalita v angličtině (část 1). Olomouc: Univerzita Palackého.