https://www.wikem.org/wiki/Main_Page
http://lifeinthefastlane.com/ecg-library/sinus-tachycardia/
http://www.ems12lead.com/2013/04/30/the-trouble-with-sinus-tachycardia/
http://www.ems12lead.com/2015/12/26/12-rhythms-of-christmas-sinus-tach/