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- An Annotated Calendar of the Letters of Charles Darwin in the Library of the American Philosophical Society
- Charles Darwin to Charles Lyell, 1847 March 7
- Charles Darwin to Charles Lyell, 1858 July 18
- Charles Darwin to Charles Lyell, 1858 June 18
- Charles Darwin to Charles Lyell, 1858 June 25
- Charles Darwin to Charles Lyell, 1858 June 26th
- Charles Darwin to Charles Lyell, 1859 October 25
- Charles Darwin to Charles Lyell, 1860 November 24
- Charles Darwin to Charles Lyell, 1860 September 28
- Charles Darwin to Charles Lyell, 1861 October 1
- Charles Darwin to Charles Lyell, 1869 March 20
![Charles Darwin to [George John] Romanes, December 16, 1874.](https://diglib-legacy.amphilsoc.org/islandora/object/text%3A1639/datastream/TN/view)
- Charles Darwin to [George John] Romanes, December 16, 1874.
- Charles R. Darwin to Charles Lyell, 1860 September 23
