Gostick, A. R., & Christopher, S. (2008). The levity effect: Why it pays to lighten up. John Wiley & Sons.
Chicago Style (17. basım) AtıfGostick, Adrian Robert, ve Scott Christopher. The Levity Effect: Why It Pays to Lighten Up. Hoboken, N.J.: John Wiley & Sons, 2008.
MLA (9th ed.) AtıfGostick, Adrian Robert, ve Scott Christopher. The Levity Effect: Why It Pays to Lighten Up. John Wiley & Sons, 2008.
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