1. C.W. Gehrke, R.W. Zumwalt, W.A. Aue, D.L. Stalling, A. Duffield, C. Ponnamperuma and K.A. Kvenvolden, Geochim. Cosmochim. Acta, in press.
2. R.W. Zumwalt, C.W. Gehrke and K. Kuo, Analysis of Nanogram Amounts of Amino Acids, manuscript in preparation.