1. Appleton, V. B. (1918). J. biol. Chem., 34, 369.
2. Drucker, P. (1923). Acta paediat., Stockh., 3, 1.
3. Elvehjem, C. A., Peterson, W. H., and Mendenhall, D. R. (1933). Amer. J. Dis. Child., 46, 105.
4. Siemers, A., and Hendenhall, D. R. (1935). Amer. J. Dis. Child., 50, 28.
5. Faxen, N. (1937). Acta paediatr., 19, Supplementum I. Guest, G. M., and Brown, E. W. (1936). Amer. J. Dis. Child., 52, 616.