| enterprise.net | 12-lead ECG library |
| vh.org | Virtual Hospital: Cardiac Catheterization |
| torrancememorial.org | Torrance Memorial Medical Center |
| themdsite.com | TheMDSite.com |
| radiologyinfo.org | RadiologyInfo: Heart and Vascular System Procedures |
| merck.com | The Merck Manual: Diagnostic Cardiovascular Procedures |
| americanheart.org | American Heart Association: Diagnostic Tests and Procedures |
| about.com | About.com: Common Heart Tests |
| ucla.edu | Ucla Heart Workup Program |
| nih.gov | Book Cmed. Table Of Contents |
| enterprise.net | homepages.enterprise.net/ |
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