Perkins, W. H. (1978). Human perpsectives in speech and language disorders. The C. V. Mosby.
Lua i Stíl Chicago (17ú heag.)Perkins, William H. Human Perpsectives in Speech and Language Disorders. The C. V. Mosby, 1978.
Lua MLA (9ú heag.)Perkins, William H. Human Perpsectives in Speech and Language Disorders. The C. V. Mosby, 1978.
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