BIBER, D. - JOHANSSON, S. - LEECH, G. - CONRAD, S. - FINEGAN, E. (1999): Longman Grammar of Spoken and Written English. Longman.
DUŠKOVÁ, L. (1999): Studies in the English Language. Karolinum - Charles University Press.
FIRBAS, J. (1992): Functional Sentence Perspective in Written and Spoken Communication. Cambridge University Press.
HUDDLESTON, R. - PULLUM, G. K. (2002): The Cambridge Grammar of the English Lan-guage. Cambridge University Press.
MATHESIUS, V. (1937): Double negation and grammatical concord. Mélanges de linguistique et philologie offerts á Jacques van Ginneken 79-83. Paris.
NEHLS, D. (1986): Semantik und Syntax des englischen Verbs, Teil II, Die Modalverben. Julius Groos, Heidelberg.
QUIRK, R. - GREENBAUM, S. - LEECH, G. - SVARTVIK, J. (1985): A Comprehensive Grammar of the English Language. Longman.
ŠMOLKA, V. (2007): The Position of Finite and Nonfinite Subject Clauses. Doctoral disser-tation, Charles University, Faculty of Arts, Dept. of English and American Studies.