1. Personal communication, R. G. Harvey, Dep. Agron., Univ. of Wisconsin, Madison, WI 53706.
2. Methods of Obtaining Field and Laboratory Germination of Seeds of Bindweeds, Lady's Thumb and Velvet Leaf
3. Personal communication, C. V. Eberlein, Dep. Agron. and Plant Genetics, Univ. of Minnesota, St. Paul, MN 55108.
4. Letters following this symbol are a WSSA-approved computer code from Important Weeds of the World, 3rd ed., 1983. Available from WSSA, 309 West Clark St., Champaign, IL 61820.
5. Personal communication, C. D. Elmore, South. Weed Sci. Lab., Agric. Res. Serv., U.S. Dep. Agric, Stoneville, MS 38776.