Jelaskan Sumber primer dari Perhambaan tani di Rusia

Gorshkov, Boris B., ed. A Life Under Russian Serfdom: Memoirs of Savva Dmitrievich Purlevskii, 1800–68. Budapest & New York, 2005

Nikitenko, Aleksandr. Up from Serfdom: My Childhood and Youth in Russia, 1804–1824 (2001)