Electrocardiogram (ECG or EKG): References

Electrocardiogram (ECG or EKG). American Heart Association. http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Electrocardiogram-ECG-or-EKG_UCM_309050_Article.jsp. Updated September 11, 2015. Accessed January 2017.

US Department of Health & Human Services. National Institutes of Health. National Heart, Lung, and Blood Institute. Electrocardiogram. https://www.nhlbi.nih.gov/health/health-topics/topics/ekg. Updated September 9, 2016. Accessed January 2017.