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Elbert Hubbard - no picture credit - Public Domain
Metallurgist - Public Domain
original uploader - Public Domain
Slowking4 -
Jonredwine - CC BY-SA 3.0
Public Domain
unknown - Public Domain
unkwown - Public Domain
Oleg Alexandrov - Public Domain
The Granite Monthly magazine - Public Domain
Wclemens - CC BY-SA 3.0
NASA - Public Domain
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Glière, Reinhold.
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Elbert Hubbard - no picture credit - Public Domain
Rogers, Henry Huttleston, 1840-1909
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Block, John R.
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Goodwin, Thomas, 1600-1680
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Metallurgist - Public Domain
Alexander, Archibald Stevens, 1906-1979
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original uploader - Public Domain
Andrews, Roy Chapman, 1884-1960
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Slowking4 -
Smith, Sally Bedell, 1948-
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Jonredwine - CC BY-SA 3.0
Albert, Don, 1908-1980
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Bussone, Francesco, approximately 1385-1432
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Public Domain
Caragiale, I.L. (Ion Luca), 1852-1912
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unknown - Public Domain
Greenhow, Rose O'Neal, 1814-1864
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Miller, Penelope Ann.
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unkwown - Public Domain
Webb, Francis William, 1836-1906
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Guise, Charles de Lorraine, duc de, 1571-1640
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Oleg Alexandrov - Public Domain
Hamilton, L. (Laurentine), 1827-1882
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Simon, Simone
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Marolles, Michel de 1600-1681
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Wistar, Caspar, 1761-1818
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The Granite Monthly magazine - Public Domain
Smith, John Butler, 1838-1914
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Sanois, Jean-François-Joseph de La Motte-Geffrard, comte de, 1723-1799
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unknown - Public Domain
Baker, Purley Albert, 1858-1924
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Mount Cashell, Stephen Moore, Earl of, 1792-1883
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Lowe, Hudson, Sir, 1769-1844
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Wclemens - CC BY-SA 3.0
Weiss, Clemens
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Bailey, Pearl
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unknown - Public Domain
Sinclair, Harry Ford
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Eddy, Jonathan, 1726 or 1727-1804
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Hall, Edmond
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NASA - Public Domain
Young, John, 1930-2018
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unknown - Public Domain
Sachs, Bernard, 1858-1944