Elena N. Nikitina. Tense and aspect of verbs of speech and perception in Russian narrative texts of 19–21 cent.
RJANO. 2014. № 2 (28), Pages. 58 - 81

Elena V. Paducheva. Is there grammatically expressed evidentiality in Russian?
RJANO. 2013. № 2 (26), Pages. 9 - 29