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On March 7 , 1918 , because of the move from Petrograd to Moscow , the Petrograd Cheka was created .
 Petrograd, Moscow, Petrograd Cheka
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Petrograd, Moscow, Petrograd Cheka