| Three photographs of “Trailer Train Company Prototype 156′ Articulated Bi-Level Auto Rack Car” (undated). |
| Information Sheet entitled “Trailer Train Company Prototype 156′ Articulated Bi-Level Auto Rack Car” Photograph of Safe-Pak Car. |
| Progressive Railroading, Dec. 1998, pp. 40-41. |
| Railway Age, Mar. 1999, pp. 30-31. |
| Progressive Railroading's 1996-1997 Car & Locomotive Yearbook and Buyers' Guide, 1996, pp. 5, 24, and 64. |
| The Car and Locomotive Cyclopedia of American Practices, Sixth Edition, 1997, pp. 7-20. |
| Whitehead & Kales Company, Drawing No. A 239-241, Dec. 16, 1972. |