1. Musk, E (2013) Hyperloop Alpha. SpaceX
2. AASHTO (2001) A policy on geometric desing of highways and streets. pp. ix (Preface)
3. LópezArchila MC, EcheverryArciniegas CA (1999) Manual de DiseñoGeométrico para Carreteras. Ciencia e IngenieríaNeogranadina 8(145–156):155
4. National Association of Australian State Road Authorities (1972) Guide Policy for Geometric Design o Freeways and Expressways
5. The Indian Road Congress (1973) Recommendations about the Alignment Survey and Geometric Design of Hill Roads