1. JamesEwing: “Neoplastic Diseases ”Third Edition 1928 page443.
2. JamesEwing:Loco citato page473.
3. D. A.Welsh: “The Surgical Pathology of the Brain and Alimentary Tract ”The Journal of the College of Surgeons of Australasia July 1929.
4. JamesEwing:Loco citato page474.