Anna L. Leontyeva, Kristina V. Litvintseva. The construction stal byt’ (‘became’) in Russian
RJANO. 2018. № 1 (35), Pages. 110 - 132

Dmitry V. Rudnev. Pseudo-copulas in the Russian of the XVIIth century
RJANO. 2012. № 2 (24), Pages. 285 - 301