1. Allerand, C.D. and Yahr, M.D. (1964) Science, l44, 1141.
2. Apnel, S.H. and Bornstein, M.B. (1964) J. exp. Med. 119, 303.
3. Astrup, T. and Piper, J. (1945) Nord. Med. 28, 2405.
4. Birkmayer, W. and Neumayer, E. (1957) Wien. Klin. Wochenschr. 69, 718.
5. Birkmayer, W., Dittrich, H. and Neumayer, E. (1958) Wien Z. Nervenheilk. 15, 59.