YU, P N G <br/><br/>
Studies of electrocardiographic changes during exercise (modified double two-step test).  [electronic resource] 

 -  Circulation  Aug 1952 
 - 183-92 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0009-7322 
<br/><br/><label>Standard No.: </label>10.1161/01.cir.6.2.183  doi 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Electrocardiography<br/>Exercise<br/>Exercise Test<br/>Humans