Organic materials and soil productivity / 
by Flaig, W. Nagar, B. Sochtig H.tietjen. 
 - Rome   FAO  1977 
 - viii, 119p. :ill  Hbk 
<br/><br/><label>ISBN: </label>9251005109 
<br/><br/><label>LC Class. No.: </label>S654.F4