1. www.rfidjournal.com/article/view/4986
2. https://www.statista.com/statistics/471264/iot-number-of-connected-devices-worldwide/
3. https://iot-analytics.com/state-of-the-iot-update-q1-q2-2018-number-of-iot-devices-now-7b/
4. https://www.ericsson.com/en/mobility-report/internet-of-things-forecast
5. E.A. Lee, Cyber physical systems: design challenges, Technical Report No. UCB/EECS-2008-8, University of California, Berkeley, 23 Jan 2008.
http://www2.eecs.berkeley.edu/Pubs/TechRpts/2008/EECS-2008-8.pdf