Hyman, Libbie Henrietta. <br/><br/>
The Invertebrates: Platyhelminthes and Rhynchocoela the Acoelomate Bilateria /  

 - 1st ed /  
 - New York :   McGraw-Hill Book Company ,   1962 
 - p.550 :  
<br/><br/><label>ISBN: </label>07-031661-9 
<br/><br/><label>Dewey Class. No.: </label>K1  / J1;1