Ermakova, Olga. “Patents, Charters, and Certificates: What Preceded the Enlistment of Foreign Nationals into the Russian Service by Contract?”. Quaestio Rossica 8, no. 5 (December 30, 2020): 1685–1694. Accessed May 3, 2024. https://qr.urfu.ru/ojs/index.php/qr/article/view/qr.552.