1. R. A. Willis, in: The spread of tumors in the human body. Butterworth, London 1973.
2. S. Paget, Lancet1, 571 (1889).
3. B. Luke, C. Breedis, Z. P. Woo, L. Berwick and P. Nowell, Cancer Res.12, 734 (1952).
4. D. L. Kinsey, Cancer13, 674 (1960).
5. H. I. Pilgrim, Cancer Res.29, 1200 (1969).