Hawkings, R.C. <br/><br/>
The maintenance of radioactive standards with the 4Ò proportional counter. 

 - Chalk River :  AECL,  1951. 
 - p. 35-44 
<br/><br/><label>ISSN: </label>0067-0367 
<br/><br/><label>Standard No.: </label>AECL-43