TY  - BOOK
AU  - Steckel, Richard H
AU  - White, William J
ED  - National Bureau of Economic Research
TI  - Engines of growth : : Farm tractors and twentieth-century U.S. economic welfare 
T2  - NBER Working Paper
PY  - 2012///
CY  - Cambridge
PB  - NBER
KW  - NBERWP 17879
KW  - E7528.pdf
UR  - http://elibrary.igidr.ac.in/e-library/working papers/NBER/2012/E7528.pdf
ER  -