Porteous, Andrew <br/><br/>
Maintaining the environment  : prepared by andrew porteous for  the technology  foundation course team 
The Open University 
 - Keynes:  The Open University Press,  1972. 
 - 105p. 
<br/><br/> PB 
<br/><br/><br/>Eng 
<br/><br/><label>ISBN: </label>335025331 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Environment <br/>Technology
<br/><br/><label>Dewey Class. No.: </label>600  / OPM