Microscopic analysis of plankton, periphyton, and activated sludge / 
US Environmental Protection Agency. 
 - [Washington] :  US Environmental Protection Agency,  1976. 
 - [S.p.] :  il. ;  27 cm. 
<br/><br/><br/>Inglés 
<br/><br/><label>Subjects--Index Terms: </label>Plancton Perifiton 
<br/><br/><label>Dewey Class. No.: </label>578.776