1. Abrahams, A. M., and Hughes, J. Howell (1952). Brit. J. Surg., 40, 68.
2. De Navasquez, S. (1936). J. Path. Bact., 42, 651.
3. Histological Appearances of Tumours;Dowd, C.N.;Ann. Surg,1915
4. Elin;Harvey, W.F.; Dawson, E.K.; Innes, J.R.M.,1940
5. Hastings-James, R. (1949). J. Path. Bact., 61, 49.