1. Chiari, H. (1897). Beit. Path. Anat., 22, 1.
2. Field, E. J. (1951). J. Anat. Lond., 85, 105.
3. Cardiovascular Studies;Franklin, K.J.,1948
4. Gaetzi, W. (1929). Ann. Anat. Strasbourg., 10.
5. Glomset, D. J., and Birge, R. F. (1948). Arch. Path. Lab. Med., 45, 135.