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2. E. Seibel: translated by J. Hitchcock, reprinted fromSteel, 1934, pp. 55–61.
3. R. Hill:The Mathematical Theory of Plasticity, Oxford University Press, 1950.
4. W. Johnson and H. Kudo:The Mechanics of Metal Extrusion, Manchester University Press, 1962.
5. B. Avitzur:Metal Forming: Process and Analysis, McGraw-Hill, New York, 1968.