ReferenceS
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- Laman J Leighty C Gittings G Heavy Axle Study: Impact of Higher Rail Car Weight Limits On Short-Line Railroads Report FHWA-PA-2001-011-97-04 (I) FHWA U. S. Department of Transportation 2001
- Cochran WG Sampling Techniques Third Edition John Wiley & Sons New York 1977
- American Railway Engineering Association Manual for Railway Engineering, American Railway Engineering Association 1996