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Alexandrov swam collegiately for the USA 's Northwestern University , from 2003 – 2007 , and has dual Bulgarian/USA citizenship .
 Alexandrov, USA, Northwestern University
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Alexandrov, USA, Northwestern University