Não informado. (1974). Communication and broadcasting. Marconi Communication Systems.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Communication and Broadcasting. Chelmsford, Inglaterra: Marconi Communication Systems, 1974.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Communication and Broadcasting. Marconi Communication Systems, 1974.
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