共 7 条
[1]
CASTER GL, 1972, AM J AGRICULTURAL EC, V54, P535
[3]
FOX KA, 1965, BROOKINGS ECONOMETRI
[4]
LANGHAM MR, 1972, ENVIRONMENTAL QUALIT, pCH5
[5]
PERELMAN M, 1972, ENVIRONMENT, V14, P13
[6]
*US DEP AGR, 1967, AGR STAT
[7]
1972, OCT S ENV QUAL FOOD