Akhlaghi, F. 200). bayestan, shodan and tavanestan: three modal verbs in the contemporary Persian, Farhangetan Letter Journal, 3 (3). 132-82. [In Persian].
Coates, J. 198). The Semantics of the Modal Auxiliaries. London and Canberra: Croom Helm.
De Haan, F. 1997. the interaction of modality and negation: a typological study. Routledge: London & New York.
Depraetere, I., & Reed, S. 2020. Mood and modality in English. In The handbook of English linguistics (2nd edition), 207-227. Wiley.
Depraetere, Ilse .2017. On the pragmatics of modal verbs. Selected papers on theoretical and applied linguistics, 22, 14-26.
Halliday, M. A. K. & Ch. M. I. M. Matthiessen .2014. Halliday’s Introduction to Functional Grammar. London and New York: Routledge.
Homayoonfar, M. 2012. investigation of the grammaticalization process in the Persian modal verbs based on Leman’s parameters. Dastoor Journal, 9, 50-73. [In Persian].
Huddleston, R. & Pullum, G. K. (Eds.) .2002. The Cambridge grammar of the English language. Cambridge: CUP.
Ilkhanipour, N,. & Karimi Doostan, Gh. 2015. lexicalization of the semantic aspects of modality in Persian modal adjectives. Language Research, 8 (19). 65-87. [In Persian].
Karimi Doostan, GH & Ilkhanipour, N. 2011. Modality System in Persian, Linguistic Research, 3 (1), 77-98. [In Persian].
Kratzer, Angelika 2012. Modals and Conditionals: New and Revised Perspectives. Oxford: OUP.
Lyons, J. 1977. Semantics (Vol. 2). CUP.
Medadian, GH. 202). subjectivity as a context-dependent semantic dimension and scalarity of modality in Persian. Language Research, 13 (39), 147-183. [In Persian].
Medadian, Gh, Nezhadansari Mahabadi, D. & Barati, H. 2017. an explicit classification of non-epistemic senses of the modal verbs tavanestan, shodan and bayestan based on Depraetere’s semantic-pragmatic model. Language Research, 10 (28), 115-148. [In Persian]
Nuyts, J. 2001. Epistemic modality, language, and conceptualization: Cognitive-pragmatic perspective. Amsterdam: John Benjamins.
Palmer, F. R. 1995. Negation and the modals of possibility and necessity. In Bybee, J. and Fleischman, S. Modality in grammar and discourse (pp. 453-471). John Benjamins: Amsterdam & Philadelphia.
Palmer, F. R. 2001. Mood and modality. Cambridge university press.
Palmer, Frank R. 1990. Modality and the English Modals. 2nd edition. London: Longman.
Rahimian, J. 2008. the formal and semantic aspects of Persian modal forms in modalized sentences. Linguistics and Dialetcs of Khorasan, 1, 75-91. [In Persian].
Rahimian, J. & Amouzadeh, M. 2012. Modal verbs in Persian language and expression of modality. Linguistic Research, 4 (1), 21-40. [In Persian].
Rahmani Parhizkar, Z., Golfam, A. & Afrashi, A. 201). the study of modality schema of Persian: a cognitive approach. Journal of Western Iranian Languages and Dialects, 1 (4), 101-118. [In Persian].
Rezae, V. & Nisani, M. 2015. Differentiating Evidentiality and Epistemic Modality Based on the Behavior of Persian Adverbials, Linguistic Studies, 7 (1), 37-56. [In Persian].
Salkie, R. (2009). Degrees of modality. In Raphael Salkie, Pierre Busuttil and Johan van der Auwera, Modality in English: Theory and description, vol. 58, (pp.79-103). Berlin & New York: Mouton de Gruyter.
Shaghaghi, V. 2001. Negation prefix in Persian. Dastoor Journal, 5 (4). 85-96. [In Persian].
Sharifi, SH. & Sabouri, N. 202). A Semantic Survey on Modal Verbs in Todays' Persian Language from a Typological Point of View. Journal of Researches in Linguistics, 13 (1), 217-230. [In Persian].
Tavangar, M., & Amouzadeh, M. 200). Subjective modality and tense in Persian. Language Sciences, 31(6), 853-873.
van der Auwera, J. 1996. Modality: the three-layered scalar square. Journal of semantics, 13(3), 181-195.
van der Auwera, J., & Plungian, V. A. 1998. Modality’s semantic map. Linguistic Typology, 2, 79–124.