 Complete the following phrase:  From 1934 to 1953, three congresses were held a breach of the party rule which stated that a congress must be convened every third year, one conference and 23 Central Committee meetings. This is in deep contrast to the Lenin era 19171924, when six Congresses were held, five conferences and 69 meetings of the Central Committee. The Politburo did not convene once between 1950, when Nikolai Voznesensky was killed, and 1953. In 1952, at the 