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A product of the Sunderland youth system , he had only a few first-team outings for Sunderland before joining Blackburn Rovers in 1976 .
 Sunderland, Sunderland, Blackburn Rovers
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Sunderland, Sunderland, Blackburn Rovers