http://www.loc.gov/exhibits/archives/repk.html

- это, что ль, документ?
http://www.loc.gov/exhibits/archives/b3bukhar.gif
- а, что ль, доказательство того, что: It is doubtful that Kirov represented an immediate threat to Stalin's predominance, but he did disagree with some of Stalin's policies, and Stalin had begun to doubt the loyalty of members of the Leningrad apparatus. In need of a pretext for launching a broad purge, Stalin evidently decided that murdering Kirov would be expedient. The murder was carried out by a young assassin named Leonid Nikolaev. Recent evidence has indicated that Stalin and the NKVD planned the crime.

но в качестве тулзы для формирование мнения - "документы", конечно, неплохие :)