Willoughby, L. G. <br/><br/>
Freshwater biology / 
L. G. Willoughby 
 - London :  Hutchinson,  1976 
 - 167 p. :  ill. ;  23 cm. 
<br/><br/>Includes bibliographical references and indexes 
<br/><br/><label>ISBN: </label>0071254310 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Freshwater biology