@article{411903, recid = {411903}, author = {Evenson, Robert E. and Gollin, Douglas.}, title = {Crop variety improvement and its effect on productivity the impact of international agricultural research / [electronic resource] :}, publisher = {CABI Pub.,}, address = {Wallingford, Oxon, UK ;}, pages = {xxv, 522 p. :}, year = {2003}, url = {http://library.usi.edu/record/411903}, }