1. S. Hadju (1979 )-Pathology of Soft Tissue Tumours , Lea and Febiger, Philadelphia, p428 .
2. E. Moulton (1978 )-Tumours in Domestic Animals , 2nd edn , Univ. California Press, Berkeley, Los Angeles, p442 .
3. W. St. C. Symmers (1979 )-Systemic Pathology , 2nd edn , Vol. 5 , Churchill Livingstone, Edinburgh, p2334 .