(2004) Evidentiality. Oxford: Oxford University Press.
Aikhenvald, A.
(2014) The grammar of knowledge: A cross-linguistic view of evidentials and the expression of information source. In A. Aikhenvald & R. M. W. Dixon (Eds.), The grammar of knowledge: A cross-linguistic typology (pp. 1–51). Oxford: Oxford University Press.
Boye, K.
(2012) Epistemic meaning: A crosslinguistic and functional-cognitive study. Berlin: De Gruyter.
(2009a) Hearsay adverbs and modality. In R. Salkie, P. Busuttil, & J. van der Auwera (Eds.), Modality in English: Theory and description (pp. 269–293). Berlin: Mouton de Gruyter.