TY  - BOOK
AU  - Martin,John Holmes
AU  - Leonard,Warren H.
TI  - Principles of field crop production / 
U1  - 633 
PY  - 1956///
CY  - New York : 
PB  - Macmillan, 
KW  - Crop production
N1  -  Includes bibliographical references and index
ER  -