Wilson, R. M. (2014). Comparison of the variations of sunspot number, number of sunspot groups, and sunspot area, 1875-2013. National Aeronautics and Space Administration, Marshall Space Flight Center.
Chicago Style (17th ed.) CitationWilson, Robert M. Comparison of the Variations of Sunspot Number, Number of Sunspot Groups, and Sunspot Area, 1875-2013. Huntsville, Alabama: National Aeronautics and Space Administration, Marshall Space Flight Center, 2014.
MLA (9th ed.) CitationWilson, Robert M. Comparison of the Variations of Sunspot Number, Number of Sunspot Groups, and Sunspot Area, 1875-2013. National Aeronautics and Space Administration, Marshall Space Flight Center, 2014.
Warning: These citations may not always be 100% accurate.