Veronika K. Skripka. The demonstrative pronoun sei in Russian official documents of the 16th–17th centuries
RJANO. 2023. № 2 (46), Pages. 281 - 292

Andrey A. Zaliznyak. Functions of the nominative flexion -a in Russian
RJANO. 2018. № 1 (35), Pages. 9 - 32