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On 16 August 1937 Obukhov was arrested in the case of Russian Catholics , and on August 31 of the same year was sentenced to death , executed on September 15 of that year near Leningrad .
 Leningrad
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Leningrad