Clarkson, E.N.K <br/><br/>
Invertebrate palaeontology and evolution 

 - 4th ed. 
 - New Delhi :  Wiley-Blackwell,       1998. 
 - xiv, 452p.  : ill. 
<br/><br/> Systematic index 435-442p.; General index 443-452p.; Reprint  2012 
<br/><br/><label>ISBN: </label>9788126533084  
<br/><br/><label>Source: </label> Textual 
<br/><br/><label>Subjects--Topical Terms: </label><br/> Class hexactinellida<br/> Mazon greek fauna<br/> Morphology and evolution<br/> Prokaryotes and eukaryotes<br/>Fossil record