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Narcissistic neurosis is a term introduced by Sigmund Freud to distinguish the class of neuroses characterised by their lack of object relations and their fixation upon the early stage of libidinal narcissism .
 Sigmund Freud
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Sigmund Freud