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Ah we concealed his identity in a way ah that it remained confidential for more than thirty years after that book came out and it only was disclosed because Mark Felt his lawyer and family decided to disclose it .
 date: more than thirty years; person: Mark Felt
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: date, organization, person, geographical social political, national religious political, facility, cardinal, location, work of art, law, event, product, ordinal, percent, time, quantity, money, language 
Text: {0} 
 Entities: more than thirty years, Mark Felt 
Answer:
 date: more than thirty years; person: Mark Felt