1. H. H. Jenkins, AREA Bull. 658,77,499-000(1976).
2. G. A. Clayton, G. H. Cope and C. O. Frederick, Railway Engineers Forum Introductory Note, ICE, London (1978).
3. A. Paterson, Proc.Symp. Railway Traffic Engineering (1968).
4. R. W. Trask, B.R. R & D Unpublished memorandum (1970).
5. R. W. Trask and T. G. Pearce, B.R. R & D Technical Memo TM DA 16 (September 1976).