Steckler, Allan <br/><br/>
The importance of external validity.  [electronic resource] 

 -  American journal of public health  Jan 2008 
 - 9-10 p.  digital 
<br/><br/> Publication Type: Editorial 
<br/><br/><label>ISSN: </label>1541-0048 
<br/><br/><label>Standard No.: </label>10.2105/AJPH.2007.126847  doi 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Periodicals as Topic--standards<br/>Public Health<br/>Research<br/>Validation Studies as Topic