| + | * Morris J, Dobson J (2001) Gastrointestinal Tract, in Small Animal Oncology, Blackwell Science, pp 137-140 |
| + | * Withrow S.J, Vail D.M (2007), Cancer of the Gastrointestinal Tract, in Withrow and MacEwen's Small Animal Clinical Oncology, fourth edition, Missouri, Saunders Elsevier, pp 483-489 |