1. Alajouanine, T., Bertrand, I., and Sabouraud, C. (1951). Rev. neurol., Paris, 84, 3.
2. Barten, H. (1934). Beitr. path. Anat., 93, 219.
3. Bielschowsky, M., and Simons, A. (1930). J. Psychol. Neurol., Lpz., 41, 50.
4. Christensen, Erna (1937). Virchows Arch. path. Anat., 300, 567.
5. Duncan, D., and Snodgrass, S. R. (1943). Arch. Neurol. Psychiat., Chicago, 50, 677.