1. Edstrom, G. (1934). Acta rheumatol., 6, 65.
2. Uppsala Ldkarefor. Forh;Edstrom, G.;Ny foljd,1944
3. Medical Disorders of the Locomotor System;Fletcher, E.,1947
4. Gram, H. C. (1942). Ugeskr. Laeg., 94, 1069.
5. Heidemann, H. (1932). Ibid., 94, 587.