Three weeks later, he began work on his dissertation for the Candidate's degree, obtaining this in June 1937, after his supervisor described the dissertation as "short and good", and the first work in its field. As a result of his efforts, he missed the 1937 Soviet championship, won by Grigory Levenfish, who was then nearly fifty. Later in 1937, Botvinnik drew a match of thirteen games against Levenfish. Accounts differ about how the match was arranged: Levenfish later wrote that Botvinnik challenged him; while Botvinnik wrote that Krylenko, angered by Botvinnik's absence from the tournament, ordered the match.