1. American Association of State Highway and Transportation Officials (AASHTO). (2004). A policy on geometric design of highways and streets, Washington, D.C., USA.
2. Bauer, K. and Harwood, D. (2014). “Safety effects of horizontal curve and grade combinations on rural two-lane highways.” Federal Highway Administration (FHWA), Report No. FHWA-HRT-13-077.
3. Bella, F. (2006). Effects of driver perception of combined curves on speed and lateral Placement, Presented at 85th Annual Meeting of the Transportation Research Board, Washington, D.C.
4. Caliendo, C., Guida, M., and Parisi, A. (2007). “A Crash-prediction model for multi-lane roads.” Accident Analysis and Prevention, Vol. 39, Issue 4, pp. 657-670, DOI: 10.1016/j.aap.2006.10.012.
5. Calinski, T. and Harabasz, J. (1974). “A dendriter method for cluster analysis.” Communications in Statistics 3, pp. 1–27, DOI: 10.1080/03610927408827101.