1. KPBC. Internet Trends 2015 – Code Conference. Available from: http://www.kpcb.com/internet-trends (last accessed 22 Feb 2016), 2015.
2. Google. Google Play. Available from: http://play.google.com/store (last accessed 22 Feb 2016), 2016.
3. Apple. iTunes. Available from: http://www.apple.com/itunes (last accessed 22 Feb 2016), 2016.
4. Gartner. Gartner Says Emerging Markets Drove Worldwide Smartphone Sales to 15.5 Percent Growth in Third Quarter of 2015. Available from: http://www.gartner.com/newsroom/id/3169417 (last accessed 23 Feb 2016), 2015.
5. GSMA, GSM Association. The Mobile Economy 2015. 2015. Available from: http://www.gsmamobileeconomy.com/GSMA_Global_Mobile_Economy_Report_2015.pdf (last accessed 24 Feb 2016).