Hearn, M <br/><br/>
Black rubber or clear plastic delivery tubing for nitrous oxide: patient preference.  [electronic resource] 

 -  International journal of obstetric anesthesia  1993 
 - 39-40 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0959-289X 
<br/><br/><label>Standard No.: </label>10.1016/0959-289x(93)90028-g  doi