TY  - JA
AU  - Dalrymple,D.G.
TI  - Changes in wheat varieties and yields in the United States, 1919-1984
SN  - 0002-1482
U1  - 89-127129 
PY  - 1988///
KW  - Crop yield
KW  - AGROVOC
KW  - Farm area
KW  - History
KW  - Production
KW  - Statistics
KW  - Technical progress
KW  - USA
KW  - Varieties
KW  - Triticum
KW  - Yields
N1  - references. Literature review
T2  - Agricultural History
ER  -