1. Azzopardi, J. G. (1966). In Recent Advances in Pathology, edited by C. V. Harrison, 8th ed., p. 98. Churchill, London.
2. Coupland, R. E. (1965). J. Anat., (Lond.) 99, 231.
3. Like, A. A. (1967). Lab. Invest., 16, 937.
4. Unpublished results;Macadam, R.F.,1967
5. Unpublished results;Macadam, R.F.,1968