Sicam, E. L. (1999). How reliable are telephone opinion polls. Philippine Daily Inquirer.
Chicago-viite (17. p.)Sicam, Edmund L. "How Reliable Are Telephone Opinion Polls." Philippine Daily Inquirer 1999.
MLA-viite (9. p.)Sicam, Edmund L. "How Reliable Are Telephone Opinion Polls." Philippine Daily Inquirer, 1999.
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