Hale, G E <br/><br/>
The Law of Sun-Spot Polarity.  [electronic resource] 

 -  Proceedings of the National Academy of Sciences of the United States of America  Jan 1924 
 - 53-5 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0027-8424 
<br/><br/><label>Standard No.: </label>10.1073/pnas.10.1.53  doi