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In 1991 he was elected into the membership of the American Academy of Arts and Letters and , in 2006 , he was elected president for a three-year term ending in 2009 .
 American Academy of Arts and Letters
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 American Academy of Arts and Letters