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National Air and Space Museum, Smithsonian Institution - Public Domain
Mathew Brady - Public Domain
R. I. Holcombe - Public Domain
Noah.levinson123usa - CC BY-SA 3.0
Ajsinclair - Public Domain
unknown - Public Domain
Bertus Esterhuysen - CC BY 3.0
Tabercil - CC BY 3.0
https://www.flickr.com/photos/punktoad - CC BY 2.0
Gobierno de Jalisco - CC BY-SA 4.0
original uploader - Public Domain
one source states - Public Domain
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Mlodinow, Leonard, 1954-....
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National Air and Space Museum, Smithsonian Institution - Public Domain
Piper, William T. (William Thomas), 1881-1970
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Nettleton, Lois
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Mathew Brady - Public Domain
Meredith, Solomon, 1810-1875
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R. I. Holcombe - Public Domain
Porter, Gilchrist, 1817-1894
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Noah.levinson123usa - CC BY-SA 3.0
Berg, Alan, 1932-
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Peraza, Armando, 1924-
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Ajsinclair - Public Domain
Herkless, John, sir, 1855-1920
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Cooper, Thomas, 1759-1839
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Laffoon, Ruby, 1869-1941
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unknown - Public Domain
Knapp, Lyman E. (Lyman Enos), 1837-1904
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Körner, Christian Gottfried, 1756-1831
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Bertus Esterhuysen - CC BY 3.0
Krog, Antjie
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Cartter, David K. (David Kellogg), 1812-1887
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Tabercil - CC BY 3.0
Mowat, Farley
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Randall, Jack, 1794-1828
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unknown - Public Domain
Ross, Adrian, 1859-1933
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Johnson, Charles Spurgeon, 1893-1956
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https://www.flickr.com/photos/punktoad - CC BY 2.0
Weitz, Paul, 1966-....
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Kahn, Otto Hermann, 1867-1934
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Gobierno de Jalisco - CC BY-SA 4.0
Nandino, Elías, 1900-1993
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original uploader - Public Domain
Maerlant, Jacob van, 1235?-1300
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Stahl, Ben, 1910-1987
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Walker, Francis, 1809-1874
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Stirling, Robert, 1790-1878
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Expilly, L. A. (Louis-Alexandre), 1743-1794
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Cooper, Emil 1877-1960
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one source states - Public Domain
Pickett, Bill, approximately 1860-1932
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Jarman, John, 1915-1982
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Bellosio, Carlo, 1801-1849.