Allen, R. (1966). The verb system of Present-day American English. The Hague: Mouton.
Bach, Cark (1985). Verbal Aspecvt. A General Theory and its Application to Present-Day English. Odense: Odense University Press.
Bach, Cark. (1995). The Study of Aspect, Tense and Action: Towards a Theory of the Semantics of Grammatical Categories. Frankfurt am Main.
Bertinetto Pier Marco (2000). Durative (non-focalized) PROG. In Dahil (2000). The Tense and Aspect in the Languages of Europ.
Bertinetto, Pier Marco, Ebert Karen H, Casper de Groot. (2000). The Progressive in Europe. In Dahil Osten Tense and Aspecvt in the in the Languages of Europ.
Comrie, Bernard (1976). Aspect An Introduction to the Study of Verbal Aspect and Related Problem. Cambridge. Combridge Univesity Press.
Comrie, B. (1981). Language Universal and Linguistiv Typology: Synatax and morphology. Chicago: University of Chicago Press.
Curme, G., O. (1931). Syntax by George O. Curme, published by: D. C. Heath and Company .
Dahil Osten (1985). Tense and Aspect System. Oxford Blackwell.
Dahil. Osten (1987). Review Article. Folia Linguistics. Series II.
Dehghān, I. (1972). Dāshtan as an auxiliary in contemporary Persian. Archiv Orientälni (Praha) 40: 198-205.
Dowty, David R. (1979). Word Meaning and Montague Grammar The Semantics of Verbs and Time in Generatives Semantics and in Montague’s PTQ. Dordrecht: Reidel.
Falhasiri, M., Y. M. & Barati, H. (2012). Second Language Acquisition of Progressive Aspect of Stative and Achievement Verbs in English. Journal of Language Teaching and Research, 3(5), 992-1003.
Farahani, Ali Akbar Khomeijani. (1990) A Syntactic and Semantic Study of the Tense and Aspect System of Modern Persian. The University of Leeds.
Hedin, E. (2000). The type-referring Function of the Imperfecrtive. In Dahil (2000) The Tense and Aspect in the Languages of Europe.
Hill, Archibald A. (1958) Introduction to linguistic structure. New youk: Harcourt, Brace.
Jespersen, Otto (1924). The philosophy of Grammar. London: George Allen and Unwin, LTD.
Jespersen, Otto (1933). Essentials of English Grammar. Londond: George Allen and Unwin. LTD.
Joos, M. (1964). The English Verb: Form and meanings, University of Wisconsin press.
Langacker, Ronald ([1991] 2002). Concept, Image, and Symbol: The Cognitive Basis of Grammar, 2nd edn. Berlin: Mouton de Gruyte.
Ljung, M. (1980). Reflection on the English progressive. Gothneburg: Gotab.
Lyons, J. (1977). Semantics I-II London. New York & Melbourne: Cambridge University Press.
Ogihara, T. (1966). Tens attitude, and Scope. USA. Springer- science + business media Dordrecht.
Ota, Akira (1963). Tense and aspect of Presend day American English. Kenkyusha Tokyo.
Smith, C. S. (1983). A theory of Aspectual choice. Linguistic Society of America. Vol. 59, NO. S. pp. 479 – 501.
Sweet, Henry (1989). A New English Grammar Vol 1 London: Oxford University Press.
Taylor, J. R. (2002). Cognitive Grammar, Oxford: Oxford University press.
Vendler. Z. (1976). Verbs and times In Z Vendler (ED), Linguistics in philosophy. Ithaca. Cambridge: Cambridge University Press.
Vlach, F. (1981). The Semantics of the Progressive. In: Tedeschi PJ and Zaenen, A. (eds.) Tense and Aspect(Syntax and Semantics 14) Academic Press New York et al. 1981, 271 – 292.
Windfuhr, G. (1979). Persian Grammar: History and state of it is study. New York: Mouton.
Zandvoort, R. W. (1962). A hand book of English Grammar. Singapore: Singapore of set printing Co. (PTE) LTD.