1. Dodd J. R. Ph.D. thesis California Institute of Technology (1961).
2. Spackman, D. H., Anal. Chem. 30: 1190 (1958).
3. Gross, J., Calcification In Biological Systems: 395 (1960).
4. Gregoire, C., J. Biophys. Biochem. Cytol. 9: 395 (1961).
5. Boggild, O. B., Kgl. Danske Videnskab. Selskabs, Skrifter Naturvidenskab. Math. Afdel. 2: 232 (1930).