1. Number of smart phone users:
https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwide/
. Accessed 06 May 2019.
2. Flight is best mode of travel:
https://www.flightnetwork.com/blog/10-reasons-flying-still-best-way-travel/
.s Accessed 06 May 2019.
3. Twitter
https://en.wikipedia.org/wiki/Twitter
. Accessed 23 Jan 2018.
4. Abel F, Gao Q, Houben G-J, Tao K (2013) Twitter-based user modeling for news recommendations. In: Rossi F
5. (ed) IJCAI 2013, proceedings of the 23rd international joint conference on artificial intelligence, Beijing, China, August 3-9, 2013.IJCAI/AAAI.