1. BURKE, J., McMAHON, B., Private Communication.
2. LAWRENCE, J. H., BARRON, R. P., CHEN, J. -Y. T., LOMBARDO, P., and BENSON, W. R., J. Ass. Offic. Anal. Chem.53, 261 (1970).
3. MILLS, P. A., ONLEY, J. H., and GAITHER, R. A., J. Ass. Offic. Anal. Chem.46, 186 (1963).
4. POLEN, P. B., HESTER, M., and BENZIGER, J., Bull. Enrivon. Contam. Toxicol.5, 521 (1970).
5. SCHWEMMER, B., COCHRANE, W. P., and POLEN, P. B., Science169, 1087 (1970).