1. Hayes, jun., W. J., Quinby, G. E., Walker, K. C., Elliott, J. W., and Upholt, W. M., Amer. Med. Assoc. Arch. Indust. Health, 18, 398 (1958).
2. Mattson, A. M., Spillane, J. T., Baker, C., and Pearce, G. W., Anal. Chem., 25, 1065 (1953).
3. Davidow, B., J. Assoc. Off. Agric. Chem., 33, 130 (1950).
4. Coulson, D. M., Cavanagh, L. A., deVries, J. E., and Walther, B., J. Agric. Food Chem., 8, 399 (1960).
5. Laug, E. P., Kunze, F. M., and Prickett, C. S., Amer. Med. Assoc. Arch. Indust. Hyg. Occup. Med., 3, 245 (1951).