共 32 条
[1]
AHEARN M, 1992, AAEA ANN M BALT MD A
[2]
Altonji JG, 1986, J POLITICAL EC, V94, P176
[3]
BOLLMAN RD, 1981, RUR SOC SOC ANN M GU
[5]
GALE F, 1991, 9119 AGES USDA