Siegrist, D. W. (1999). The threat of biological attack: Why concern now? Centers for Disease Control and Prevention.
Chicago-tyylinen lähdeviittausSiegrist, D W. The Threat of Biological Attack: Why Concern Now? Centers for Disease Control and Prevention, 1999.
MLA-viiteSiegrist, D W. The Threat of Biological Attack: Why Concern Now? Centers for Disease Control and Prevention, 1999.
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