1. About One-in-five Americans Use a Smart Watch or Fitness Trackerhttps://www.pewresearch.org/fact-tank/2020/01/09/about-one-in-five-americans-use-a-smart-watch-or-fitness-tracker/
2. Wearable Devices Market by Product Type (Smartwatch, Earwear, Eyewear, and others), End-Use Industry (Consumer Electronics, Healthcare, Enterprise and Industrial, Media and Entertainment), Connectivity Medium, and Region—Global Forecast to 2025https://www.meticulousresearch.com/product/wearable-devices-market-5050
3. Approximation by superpositions of a sigmoidal function
4. Recurrent Neural Networks Are Universal Approximators;Schäfer,2006
5. Universality of deep convolutional neural networks