1. G. Gauthier,Found. Trade J. 59, 373 (1938).
2. J. Calvet and V. Potempkine,Rech. Aeron. 29, 21 (1952).
3. M. Whitaker and A. R. Heath,J. Inst. Metals 82, 107 (1953?1954).
4. E. A. Smith, Jr.,Light Metal Age 12, 24 (1954).
5. S. Balicki,Prace. Inst. Hutniczych 10, 208 (1958).