(1975). Mental retardation: The known and the unknown : information as of February 1, 1975.
Chicago-viite (17. p.)Mental Retardation: The Known and the Unknown : Information as of February 1, 1975. 1975.
MLA-viite (9. p.)Mental Retardation: The Known and the Unknown : Information as of February 1, 1975. 1975.
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