1. Aaker, D.A., Kumar, V., Day, G.S., 2001. Marketing Research (7th ed.). New York, John Wiley and Son Inc.
2. Agresti, A., 2007. An Introduction to Categorical Data Analysis: Second Edition. John Willey and Sons, Inc., Hoboken, New Jersey.
3. Aidoo, E.N., Agyemang, W., Monkah, J.E., Afukaar, F.K., 2013. Passenger's satisfaction with public bus transport services in Ghana: A case study of Kumasi-Accra route. Theoretical and Empirical Researches in Urban Management. 8(2): 33-44.
4. Bang, H.Q., 2014. Calculate Road Traffic Air Emissions Including Traffic jam: Application over Hồ Chí Minh City, Vietnam. VNU Journal of Science: Earth and Environmental Sciences. 30(1): 12-21.
5. Barabino, B., Deiana, E., 2012. On the attributes and influencing factors of end-users quality perceptions in urban transport: An exploratory analysis. Social and behavior sciences. 87: 18-30.