1999, Chester Peterson, Rod Beemer, ''Inside John Deere: A Factory History'', page 93,
- The fleet has 48 semi-tractors and 164 trailers that transport 110,000 tons of parts and supplies annually over 1 million miles of roads.
2003, Michael E. Gray, ''Auto Upkeep: Basic Car Care'', page 56,
- Some people think diesel fuel is only used in semi-tractors (''Figure 9.3'') or heavy equipment.
2008, Raymond P. Siljander, ''Introduction to Business and Industrial Security and Loss Control'', 2nd Edition, page 75,
- Security seal use applies when carrying merchandise in semi-truck trailers (highway trailers) pulled by semi-tractors and when railroad flatcars carry the trailers, the latter referred to as piggyback (piggybacking).