1. Stewart , H. E. and Selig , E. T.“Predictions of track settlement under traffic loading”,Second International Heavy-Haul Railway Conference, Colorado Springs , September 1982 , pp 488 – 496 .
2. Selig , E. T. and Alva-Hurtado , J. E.“Predicting effects of repeated wheel loading on track settlement”, 2nd International Heavy-Haul Railway Conference , Colorado Springs , September 1982 , pp 476 – 487 .
3. “Manual of standards and accepted practices” AAR specification M001, Section C - part IL Chapter 11, The Association of American Railroads.