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2. W. Watt, L. N. Philips, and W. Johnson, The Engineer 221 (1966) 815.
3. W. Johnson, L. N. Philips, and W. Watt, U.K. Pat. 1,110,791 (1968).
4. W. Watt, paper presented at IP & PS Conference ?Fibres for Composites?, Brighton, June 1969.
5. Idem, Nature 222 (1969) 265.