1. Boas, N. F., and Foley, J. B. (1954) Proc Soc. exp. Biol. (N.Y.), 86, 690.
2. Boyle, P. J., Conway, E. J., Kane, F., and O'Reilly, H. L. (1941).
3. "Proc. II Int;Brendstrup, P.;Congr. Physical Med., Copenhagen,1957
4. Glogowski, G., and Wallraff, J. (1951). Ztschr. Ortopadie, 80, 237.
5. Lange, F. (1925). Munch. med. Wschr., 72, 1626.