Hedeman, E. Ruth <br/><br/>
Evolutionary charts of solar activity (calcium plages) as functions of heliographic longitude and time, 1964-1979 / 
E. Ruth Hedeman, Helen W. Dodson, Edmond C. Roelof. 
 - Boulder, Colorado :  U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Environmental Data and Information Service, World Data Center A for Solar-Terrestrial Physics, NOAA,  1981. 
<br/><br/>Report UAG, 81. 
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