1. K. Al-Khatib, J. R. Baumgartner, D. E. Peterson, and R. S. Currie .1998 .Imazethapyr resistance in common sunflower (Helianthus annus)., Weed Sci, 46 :403 –407 .
2. Herbicide Contamination of Groundwater Beneath Claypan Soils in North‐Central Missouri
3. P. R. Bradley, W. G. Johnson, S. E. Hart, M. L. Buesinger, and R. E. Massey .2000 .Economics of weed management in glufosinate-resistant corn (Zea mays L)., Weed Technol, 14 :495 –501 .
4. P. R. Bradley, W. G. Johnson, J. D. Wait, C. S. Holman, and J. W. Niekamp .1997a .Weed management in glufosinate tolerant corn., N. Cent. Weed Sci. Soc. Res. Rep, 54 :156 –157 .
5. P. R. Bradley, W. G. Johnson, J. D. Wait, C. S. Holman, and J. W. Niekamp .1997b .Weed management in glyphosate tolerant corn., N. Cent. Weed Sci. Soc. Res. Rep, 54 :146 –147 .