1. Cognitive English Grammar;Radden,2007
2. A comparison analysis of modal auxiliary verbs in technical and general English;Jaime;Procedia - Social and Behavioral Sciences,2015
3. The effects of essay topics on modal verb uses in L1 and L2 academic writing;Hinkel;J. Pragmat.,2009
4. Adverbs and Modality in English;Hoye,2014
5. My opinion: modality in Japanese EFL learners' argumentative essays, asia pacific journal of corpus research;Pemberton,2020