Drew, C. J., Hardman, M. L., & Logan, D. R. (1988). Mental retardation: A life cycle approach (4th ed.). Merrill.
Lua i Stíl Chicago (17ú heag.)Drew, Clifford J., Michael L. Hardman, agus Donald R. Logan. Mental Retardation: A Life Cycle Approach. 4th ed. Columbus, Ohio: Merrill, 1988.
Lua MLA (9ú heag.)Drew, Clifford J., et al. Mental Retardation: A Life Cycle Approach. 4th ed. Merrill, 1988.
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