1. WHO Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death, seventh revision (WHO, Geneva, 1957).
2. Stout, A. P., Tumors of the Soft Tissue, Atlas of Tumor Pathology, Section II—Fascicle 5 (AFIP, Washington, 1953).
3. Ringertz, N., Ericsson, J., Sjöstrom, A., and Swenson, D., Cancer Incidence in Sweden 1961 (National Board of Health, the Cancer Registry, Stockholm, 1965).
4. Eidson, C. S., Schmittle, S. C., Goode, R. B., and Lal, J. B., Amer. J. Vet. Res., 29, 1053 (1966).
5. Banfield, W. G., Woke, P. A., and MacKay, C. M., Cancer, 19, 1333 (1966).