1. Annual Book of ASTM Standards, Vol. 8.04 (1988) p. D2837.
2. Ibid., Vol. 8.04 (1988) p. D2290.
3. Ibid., Vol. 8.04 (1988) p. D2412.
4. Ibid., Vol. 8.02 (1988) p. D1693.
5. K. G. Toll, E. F. Palermo andG. T. Appelton, in Proceedings of 10th Plastic Fuel Gas Pipe Symposium, New Orleans, October 1987 (American Gas Association, 1987) p. 142.