1. M. M. ALLEN: Proc. AGARD Conf. No. 200 on 'Advanced fabrication techniques in powder metallurgy and their economic implications', April 1976, Paper 5, pp. 1–15.
2. J. S. BENJAMIN and J. M. LARSON: AIAA Aircraft Systems and Technology Meeting, Texas, September 1976.
3. C. H. SYMONDS and F. A. THOMPSON: Ref. 3, paper 3, pp. 1–14.