1. D. Sencer: Statement to Senate Subcommittee on Anti-Trust and Monopoly (Committee on the Judiciary), Washington, D.C. (1967)
2. A. K. Parpart: Science 113, 483–484 (1951)
3. L. E. Flory: Proc. IRE 47, 1889–1894 (1959)
4. C. Berkley: ”Electronic Counting, Sorting and Sizing“; Proc. 2nd Intern. Conf. Med. Electron. (Iliffe and Sons, Ltd., London 1959)
5. P.O. B. Montgomery (ed.): Ann. New York Acad. Sci. 97, 329–526 (1962)