Penenberg, Adam L. <br/><br/>
Viral loop :  the power of pass-it-on /​ 
Adam L. Penenberg. 
 - London :  Sceptre,  2010. 
 - ix, 274 p. ;  20 cm. 
<br/><br/>Includes bibliographical references and index. 
<br/><br/><label>ISBN: </label>9780340918692