1. World Health Organization (WHO). “Deafness and hearing loss,” 2018, [Online]. Available: http://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss.
2. MikePrice. “The 5 Best Hearing Impaired Alert Devices,” 2018. [Online]. Available: https://www.rehabmart.com/post/the-5-best-hearing-impaired-alert-devices.
3. SARA, Situational Awareness and Response Assistant. 2019. [Online]. Available: http://www.statussolutions.com/technologies/automated-alerting.
4. DIY Emergency Buttons for the Elderly. 2019. [Online]. Available: https://www.medicalalertadvice.com/resources/diy-emergency-buttons-for-the-elderly/.
5. Emergency Button for 7$, Arduino, WIFI and ESP8266. 2019. [Online]. Available: https://www.instructables.com/id/Emergency-Button/.