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A longtime labor advocate , he became vice-president of the International Brotherhood of Pulp , Sulphite , and Paper Mill Workers and its successor , the United Paperworkers International Union .
 United Paperworkers International Union
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 United Paperworkers International Union