Unwin, Ernest E. <br/><br/>
Pond problems / 
Ernest E. Unwin. 
 - United Kingdom :  Cambridge University Press,  2014. 
 - 119 p. :  ill. ;  20 cm. 
 - The Cambridge Nature Study series .
<br/><br/>Includes bibliographies and index 
<br/><br/><label>ISBN: </label>9781107642249 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Entomology.<br/>Life Sciences.<br/>Zoology.