1. Ambrazas, V. (ed.). 2006. Dabartinės lietuvių kalbos gramatika. Vilnius: Baltos lankos.
2. Bellés-Fortuño, B., I. Fortanet-Gómez. 2005. Spoken academic discourse: An approach to research on lectures. Revista española de lingüística aplicada 1, 161-178, https://dialnet.unirioja.es/descarga/articulo/1998029.pdf
3. Bellés-Fortuño, B. 2016. Academic discourse markers: A contrastive analysis of the discourse marker 'then' in English and Spanish lectures. Verbeia 1, 57-78, https://www.ucjc.edu/wp-content/uploads/3.-Begona-Belles-Fortuno.pdf
4. Biber, D., S. Johansson, G. Leech, S. Conrad, E. Finnegan, R. Quirk. 1999. Longman Grammar of Spoken and Written English. London: Longman.
5. Brown, P., S. C. Levinson. 1987. Politeness: Some universals in language usage 4. Cambridge: Cambridge University Press.