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unknown - Public Domain
Gage Skidmore - CC BY-SA 3.0
Mathew Brady Levin Corot Handy - Public Domain
Jeffrey Martin - Public Domain
Heinrich Kley (1863-1945) - Public Domain
Daniel J. Strain - Public Domain
Dxede5x - CC BY-SA 3.0
Olaf Kosinsky/AutorOK - CC BY-SA 3.0
https://www.flickr.com/photos/vagueonthehow/ - CC BY 2.0
Bassano Ltd (active 1901-1962). - Public Domain
the Oxford Dictionary of National Biography - Public Domain
William Strang (1859-1921) - Public Domain
here - Public Domain
Charles S. Rawson - Public Domain
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Ajdukiewicz, Tadeusz (1852-1916).
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unknown - Public Domain
Bass, Sam, 1851-1878
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Petrović, Aleksandar, 1929-1994
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Gage Skidmore - CC BY-SA 3.0
Brandt, Betsy
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Nichols, Rose Standish
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Mathew Brady Levin Corot Handy - Public Domain
Pomeroy, S. C. (Samuel Clarke), 1816-1891
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Pivert, Marceau, 1895-1958
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Jeffrey Martin - Public Domain
Rose, Charles G., 1939-2012
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Brassin, Louis, 1840-1884
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Heinrich Kley (1863-1945) - Public Domain
Kley, Heinrich, 1863-1945
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Jaspers, Karl, 1883-1969
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Hone, Philip, 1780-1851
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Daniel J. Strain - Public Domain
Robinson, George D. (George Dexter), 1834-1896
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Dxede5x - CC BY-SA 3.0
Louvin, Charlie, 1927-2011
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Bustamante, Carlos María de, 1774-1848
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McReynolds, James Clark, 1862-1946
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Olaf Kosinsky/AutorOK - CC BY-SA 3.0
Jahn, Thomas, 1965-
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https://www.flickr.com/photos/vagueonthehow/ - CC BY 2.0
Connell, Alan
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Dutronc, Jacques
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Bassano Ltd (active 1901-1962). - Public Domain
Horobin, Ian, 1899-1976
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Essenius, Andreas, 1618-1677
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unknown - Public Domain
Perry, Mr. (William Hayne), 1839-1902
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the Oxford Dictionary of National Biography - Public Domain
Müller, F. Max (Friedrich Max), 1823-1900
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William Strang (1859-1921) - Public Domain
Trefusis, Violet, 1894-1972
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Hofer, Johanna, 1896-1988
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Donaldson, Jesse M. (Jesse Monroe), 1885-1970
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here - Public Domain
Meigs, Return Jonathan, 1740-1823
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Heysen, Nora, 1911-
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Reimarus, Johann Albert Heinrich, 1729-1814
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Charles S. Rawson - Public Domain
Doane, William Croswell, 1832-1913