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The party had been formed on 21 April 1946 by the merger of the SPD in the Soviet occupation zone with the Communist Party of Germany ( KPD ) , strongly backed by the Soviet authorities .
 Soviet occupation zone, Communist Party of 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:
 Soviet occupation zone, Communist Party of Germany