Annals of the IGY  vol. XXII, solar activity maps D2 
edited by M. A. Ellison                                            
 - London  Pergamon Press  1962 
<br/><br/><label>Subjects--Topical Terms: </label><br/>International Geophysical Year<br/>Map<br/>Solar-activity
<br/><br/><label>Universal Decimal Class. No.: </label>523.745  / ELL-22