1. DTI (compiled M. Neale), Presentation at Friction and Wear Forum, NPL, Teddington, 1997.
2. Jost, UK Department of Education and Science, Lubrication (Tribology): Education and Research, HMSO, 1966.
3. R.J. Percy, The Operational Performance of BP Choke Valves, BP Engineering, Risers and Subsea Equipment Group, 1990 BPE.90.ER152, submitted for publication.
4. H.A. Gordon, H.M. Gordon, Conduit or pipe, US Patent Number 630,605 (1899).
5. A.W. Robinson, Delivery pipe for hydraulic dredging machines, US Patent Number 1,451,272 (1923).