1. Lamkin P.: Wearable Tech Market To Be Worth $34 Billion By 2020.
https://www.forbes.com/sites/paullamkin/2016/02/17/wearable-tech-market-to-be-worth-34-billion-by-2020/#4cbe76e83cb5
(2016)
2. Tractica: Healthcare Wearable Device Shipments to Reach 98 Million Units Annually by 2021.
https://www.tractica.com/newsroom/press-releases/healthcare-wearable-device-shipments-to-reach-98-million-units-annually-by-2021/
(2016)
3. Haydon, R.: Bluetooth Low Energy: the Developer’s Handbook. Pearson Education, Brooklyn (2013)
4. IEEE Standard for Low-Rate Wireless Networks, "IEEE Std 802.15.4–2015 (Revision of IEEE Std 802.15.4–2011)” (2016)
5. ZigBee Alliance,
http://www.zigbee.org/