TY  - BOOK
AU  - Evenson R E Ed.
AU  -  Gollin D Ed.
TI  - Crop variety improvement and its effect on productivity :  The impacat of international agricutural research.     
U1  - J3:5, P3 
PY  - 2003///
CY  - Wallingford
PB  - CABI Publishing      
ER  -