1. 2020 Public Transportation Fact Book. American Public Transportation Association. Available at: https://mk0aptacoma227k83f08.kinstacdn.com/wp-content/uploads/APTA-2020-Fact-Book.pdf.
2. Table 236.90 Students transported at public expense and current expenditures for transportation: Selected years, 1929-30 through 2015-16. National Center for Education Statistics. Available at: https://nces.ed.gov/programs/digest/d18/tables/dt18_236.90.asp.
3. School Bus Safety. National Highway Traffic Safety Administration. Available at: https://www.nhtsa.gov/road-safety/school-buses.
4. Incidence and characteristics of school bus crashes and injuries;Yang;Accid Anal Prev,2009
5. NHTSA Report to Congress, School Bus Safety: Crashworthiness Research, April 2002. U.S. Department of Transportation. Available at: https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/sbreportfinal.pdf.