TY  - BOOK
AU  - C.A. Black
AU  -  G.E. Van Riper W.C. Burrows  R.F. Holland
TI  - Agronomy in a changing world and research needs for the seventies
U1  - 630 
PY  - 1971///
CY  - Madison
PB  - American Society of Agronomy
ER  -