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Wolfers holds a Ph.D. in Economics ( 1997-2001 ) and an A.M in Economics ( 2000 ) , both from Harvard University , and a Bachelor of Economics ( First class honors and University medal ; Majors in economics , law and computer science ) from the University of Sydney ( 1991-1994 ) .
 Wolfers, Harvard University, University of Sydney
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Wolfers, Harvard University, University of Sydney