1. Division of Biologics Standards, and the National Cancer Institute, National Institutes of Health, Bethesda, Md.
2. Harvard Medical School, Boston, Mass.
3. National Cancer Institute, National Institute of health, Bethesda, Md.
4. National Cancer Institute, National Institutes of Health, Bethesda, Md.
5. Medicine Branch, National Cancer Institute, National Institute of Health, Bethesda, Md.