2Creech J E, Johnson W G. Survey of broadleaf winter weeds in Indiana production fields infested with soybean cyst nematode (Heterodera glycines)[J]. Weed Technology, 2006,20 (4) : 1066 - 1075.
3Davis V M, Gibson K D, Johnson W G. A field survey to de- termine distribution and frequency of glyphosate - resistant horseweed(Conyzacanadensis) in Indiana [J]. Weed Technol- ogy, 2008,22(2) :331 - 338.