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Konrad Jacobs - CC BY-SA 2.0
Teinesavaii - CC BY-SA 3.0
Colmer, Montagu, and Charles Erskine Scott Wood - Public Domain
Engraved by Welch & Walters from a daguerreotype by M. P. Simmons - Public Domain
Internet Archive Book Images -
original uploader en:Rsabbatini - Public Domain
unknown - Public Domain
Simon Gribelin - Public Domain
Politikundtheorie - CC BY-SA 4.0
Alexandre Dulaunoy - CC BY-SA 2.0
C.W. Bardeen, publisher - Public Domain
Doug Hall - CC0 1.0
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Konrad Jacobs - CC BY-SA 2.0
Hasse, Helmut, 1898-1979
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Teinesavaii - CC BY-SA 3.0
Henry, Albert, Sir, 1907-
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Colmer, Montagu, and Charles Erskine Scott Wood - Public Domain
Pratt, Orville C. (Orville Charles), 1819-1891
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Engraved by Welch & Walters from a daguerreotype by M. P. Simmons - Public Domain
Chapman, Nathaniel, 1780-1853
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Internet Archive Book Images -
Newell, Frederick Haynes, 1862-1932
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Roach, Jay
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Stuart, George Okill, 1807-1884
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original uploader en:Rsabbatini - Public Domain
Koenig, Rudolph, 1832-1901
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Robinson, George Augustus, -1866
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unknown - Public Domain
Peretz, Isaac Leib, 1851 or 1852-1915
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unknown - Public Domain
Saunders, Romulus Mitchell, 1791-1867.
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Annadurai, C. N., 1909-1969
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unknown - Public Domain
Parsons, Lucy E. (Lucy Eldine), 1853-1942
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Spence, Basil, Sir, 1907-1976
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Adelard, of Bath, approximately 1116-1142
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Ford, Ruth, 1911-2009
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Everest, George, Sir, 1790-1866
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Simon Gribelin - Public Domain
Hudson, John, 1662-1719
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Politikundtheorie - CC BY-SA 4.0
Brown, Wendy, 1955-....
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Alexandre Dulaunoy - CC BY-SA 2.0
Mentelin, Johann, approximately 1410-1478
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Forster, William, 1784-1854
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Calder, Alexander, 1898-1976
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C.W. Bardeen, publisher - Public Domain
Fröbel, Friedrich, 1782-1852
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Bossi, Enea, 1888-1963
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Diane, de France, 1538-1619
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Litvak, Anatole, 1902-1974
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Greenhouse, Linda.
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Doug Hall - CC0 1.0
Hall, Doug, 1944-
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unknown - Public Domain
Bodenheimer, Max, 1865-1940
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Taylor, T. E.