1. Cancellative discourse markers: a core/periphery approach;Bell;Pragmatics,1998
2. Bell, David. M. 2006. Nevertheless, Still and Yet: Concessive Cancellative Discourse Markers. Unpublished MS: Ohio University.
3. Longman Grammar of Spoken and Written English;Biber,1999
4. From aspectuality to discourse marking: the case of French ‘déjà’ and ‘encore’;Mosegaard Hansen;Belgian Journal of Linguistics,2003
5. A Comprehensive Grammar of the English Language;Quirk,1985