1. 1. CS Farrow, R Green, and M. Shively, Radiology of the cat . St. Louis, MO: Mosby-Year Book, 1994 ;139 .
2. 2. TR. O'Brien, Radiographic diagnosis of the abdominal disorders in the dog and cat . Philadelphia: WB Saunders Company, 1981 ;204 -278 .
3. Mach Bands and Density Perception
4. Boundaries in the Radiographic Image