Smith, P A <br/><br/>
Homotopy Groups of Certain Algebraic Systems.  [electronic resource] 

 -  Proceedings of the National Academy of Sciences of the United States of America  Jul 1949 
 - 405-8 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0027-8424 
<br/><br/><label>Standard No.: </label>10.1073/pnas.35.7.405  doi