https://jamanetwork.com/journals/jamacardiology/fullarticle/2566167 – a

https://jamanetwork.com/journals/jama/fullarticle/2695678

https://www.bmj.com/content/362/bmj.k2986

http://www.drjohnm.org/2017/12/thoughts-on-the-apple-watch-and-mobile-ecg/