TY  - BOOK
AU  - Gray, R. B.
TI  - The agricultural tractor, 1855-1950
U1  - 631.372 
PY  - 1974///(c.1954)
CY  - St. Joseph, Mich.,
PB  - American Society of Agricultural Engineers
KW  - Maquinaria agrícola
KW  - Historia
KW  - Tractores
ER  -