With April designated Poetry Month, it is a good time to call attention to the Library of Congress's site on Walt Whitman Notebooks from the 1850s and 1860s. These notebooks were stolen from the Library of Congress in the 1940s but reappeared in 1995. There is information on the site explaining how the notebooks are being preserved, and lots of supporting information about Whitman and how he wrote and edited his poetry. It is all available at:
http://memory.loc.gov/ammem/collections/whitman/