1. Electric scooters are going worldwide;Dickey,2018
2. The casualties from electric bike and motorized scooter road accidents;Siman-Tov;Traffic Inj Prev,2017
3. To serve and protect, perched on 3 wheels;Kaminer,2010
4. Raphelson, S. (2018, August 29). Dockless scooters gain popularity and scorn across the U.S. Retrieved from https://www.npr.org/2018/08/29/643058414/dockless-scooters-gain-popularity-and-scorn-across-the-u-s
5. Irfan, U. (2018, September 07). Electric scooters' sudden invasion of American cities, explained. Retrieved from https://www.vox.com/2018/8/27/17676670/electric-scooter-rental-bird-lime-skip-spin-cities