Hay margaret <br/><br/>
An introduction to the physiology of crop yield 

 - New york  Longman  1989 
<br/><br/><label>ISBN: </label>0-582-40808-3 
<br/><br/><label>LC Class. No.: </label>633/HAY 
<br/><br/><label>Dewey Class. No.: </label>633/HAY