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Popularity in communist countries After World War II , Ivens spent several years in East Germany , where he edited Song of the Rivers , which is said to have been seen by 250 million people in communist countries .
 Ivens, East Germany
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Ivens, East Germany