1. Unpublished data;Bywaters, E.G.L.,1939
2. Day, S. B., Hinshaw, L. B., and Walder, A. (1960).
3. The Pathology and Surgery of the Veins of the Lower Limb.;Dodd, H.; Cockett, F.B.,1956
4. Muller, W. (1929). Dsch. Z. Chair 218, 395.
5. Ranke, H. R. (1875). Zbl. Chir., 2, 609.