1. Mitchell, W. J., Borroni-Bird, C. E. & Burns, L. D. Reinventing the Automobile: Personal Mobility for the 21st Century (MIT Press, 2010).
2. Sacks, D. 'The Sharing Economy' Fast Company (18 April 2011); available at
http://go.nature.com/co6pte
.
3. Summary of Travel Trends: 2009 National Household Travel Survey (US Department of Transportation Federal Highway Administration, 2011).
4. Shankar, V. Strategic Analysis and Benchmarking of Global OEMs Micro-Mobility Solutions (Frost & Sullivan, 2012).
5. Burns, L. D., Jordan, W. C. & Scarborough, B. A. Transforming Personal Mobility (Earth Institute, Columbia University, 2013).