1. Gray, C. H., and Nicholson, D. C., J. Chem. Soc., 627, 3085 (1958).
2. Gray, C. H., Bile Pigments in Health and Disease, 29 (American Lectures in Living Chemistry. Charles C. Thomas, U.S.A., 1961).
3. Siedel, W., and Meier, E., Z. Physiol. Chem., 242, 101 (1936).
4. Jackson, A. H., Kenner, G. W., and Nicholson, D. C. (unpublished observations of nuclear magnetic resonance spectra).
5. Watson, C. J., J. Biol. Chem., 105, 469 (1934).