Agricultural systems :  heterogeneity and diversity in less-favour ed areas / 
guest editor, Herman van Keulen. 
 - London :  Elservier,  2005. 
 - 19 p. :  ill. ;  30 cm. 
<br/><br/> Available online at www.sciencedirect.com 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Agriculture-- Economic aspects.