美国农业部下属经济研究中心
Pesticide Use & Markets http://www.ers.usda.gov/topics/farm-practices-management/chemical-inputs/pesticide-use-markets.aspx#.UZMxd0QtC5A
Pesticide Use & Markets http://www.ers.usda.gov/topics/farm-practices-management/chemical-inputs/pesticide-use-markets.aspx#.UZMxd0QtC5A