1. Urbanizationhttps://www.researchgate.net/publication/226167135_Urbanization
2. The Future of Urban Mobility: Towards Networked, Multimodal Cities of 2050https://robertoigarza.files.wordpress.com/2009/07/rep-the-future-of-urban-mobility-2050-little-2011.pdf
3. Passenger Cars, by Type of Motor Energyhttp://ec.europa.eu/eurostat/data/database
4. BP Energy Outlook 2015https://www.bp.com/en/global/corporate/energy-economics/energy-outlook.html
5. Travel behaviour and health: A conceptual model and research agenda