Kwok, S <br/><br/>
Cosmic butterflies : the colorful mysteries of planetary nebulae 
Sun Kwok 
 - Cambridge  Cambridge University Press  2001 
 - ix, 179 p. : col. ill. ; 27 cm 
<br/><br/> Includes bibliographical references (p. [169]-170) and index 
<br/><br/><label>ISBN: </label>521791359 
<br/><br/><label>ISSN: </label>68867 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Planetary nebulae
<br/><br/><label>Dewey Class. No.: </label>523.1135 KWO