Harvey, R. B., Larso, A. H., Landon, R. H., Boyd, W. L., Erickson, L. C. 1945. Weeds Poisonous to Livestock. Bull. Minnesota Agr. Exp. Sta., 388: 1.
*Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.