Retraction:   [electronic resource] 

 -  Regional anesthesia and pain medicine  May 2019 
 - e1 p.  digital 
<br/><br/> Publication Type: Journal Article; Retraction Notice 
<br/><br/><label>ISSN: </label>1532-8651 
<br/><br/><label>Standard No.: </label>10.1136/rapm-2018-100229ret  doi