1. Albert, E. (1893). Wien. med. Pr., 34, 41.
2. Berenwenger, P. (1930). Arch. klin. Chir., 159, 472.
3. Blencke, A. (1908). Z. Orthop. Chir., 20, 363.
4. Unpublished observations;Dresner, E.; Bywaters, E.G.L.,1953
5. Franke, F. (1895). Arch. klin. Chir., 49, 487.