1. J. Bowman, in ?Proceedings of the 11th Plastic Fuel Gas Pipe Symposium?, 3?5 October 1989, San Francisco, organized by the American Gas Association p. 235.
2. E. R. Jones andW. L. Bradley,Forensic Engng 1 (1987) 47.
3. W. A. A. Sewers andWater Mains Committee: ?Materials and Standards?: No. 4-32-05 April 1986; Issue 1 ISSN 0267-0305.
4. J. M. Greig andC. C. Lawrence, in ?International Conference on Plastics Pipes VII? 19?22 September 1988, University of Bath (P.R.I.) paper 14.
5. A. Lustiger andR. D. Corneliussen,J. Mat. Sci. 22 (1987) 2470.