Gostick, Adrian Robert. The levity effect : why it pays to lighten up / Adrian Gostick and Scott Christopher. - Hoboken, N.J. : John Wiley & Sons, c2008. - viii, 229 p. : ill. ; 22 cm. Includes bibliographical references. ISBN: 9780470195888 LCCN: 2007051424 Subjects--Topical Terms: Humor in the workplace. Dewey Class. No.: 658.45 / GOL