@article {634, title = {A Photographic Periodogram of the Sun-Spot Numbers}, journal = {The Astrophysical Journal, }, volume = {XL }, year = {1914}, keywords = {Douglass, numbers, periodogram, photo, photographic, spot, sun, sun spot}, author = {Douglass, A.E.} } @article {798, title = {Indications of a Rainy Period in Southern Peru}, volume = {XX}, year = {1892}, keywords = {climate, Douglass, environment, historic, peru, sun spot}, author = {Douglass, A.E.} }