1. DORN, C.R., PIERCE, J.O. II, CHASE, G.R., and PHILLIPS, P.E.,In Hemphill, D.D. (ed.) Proc. 7th Annual Conf. Trace Subst. Environ. Health, Univ. Missouri, Columbia (in press).
2. HALL, R.F., SANDERS, W.L., BELL, M.C., and REYNOLDS, R.A., Amer. J. Vet. Res.32, 1613 (1971).
3. HAMMER, D.I., FINKLEA, J.K., HENDRICKS, R.H., SHY, C.M., and HORTON, R.J.M., Amer. J. Epid.93, 84 (1971).
4. HARTMAN, J., Jarrb. Inst. Biol. Scheik. Onderg. Land. p. 113 (1967).
5. HEMPHILL, D.D., MARIENFELD, C.J., REDDY, R.S., HEIDLAGE, W.D., and PIERCE, J.O. II, J. Assoc. Official Analyt. Chemists56, 994 (1973).