1. Aijmer, Karin, in press. Modal adverbs in interaction—obviously and definitely in adolescent speech. In: Nevalainen, Terttu, Taavitsainen, Irma, Pahta, Päivi, Korhonen, Minna (Eds.), The Dynamics of Linguistic Variation: Corpus evidence on English past and present. John Benjamins, Amsterdam/Philadelphia.
2. Amplifier collocations in spoken English;Altenberg,1991
3. Longman Grammar of Spoken and Written English;Biber,1999
4. Degree Words;Bolinger,1972
5. On certainly and zeker;Byloo,2007