Biblio
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Author Title Type [ Year
Filters: Author is Douglass, A.E. and Keyword is sun spot [Clear All Filters]
“A Photographic Periodogram Of The Sun-Spot Numbers”. The Astrophysical Journal, XL (No. 3). The Astrophysical Journal, .
. 1914. 
“Indications Of A Rainy Period In Southern Peru”. Science. Science.
. 1892. 