Nuffield Advanced Science :   biological science ; key to pond orga nisms /  
Alison  Leadley Brown 
 - London :   Penguin Books,   1970 
 - 45 p. :    ill. ;    21 cm. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Freshwater invertebrates --------Identification<br/>Freshwater plants --------Identification
<br/><br/><label>Dewey Class. No.: </label>574.07 NUF