Henri Poincaré's manuscripts
Henri Poincaré's Nachlass includes dozens of manuscripts, including reports, research notes, course notes, calculations, and drafts of scientific papers.
The search engine on the left lets you search for a manuscript in two modes: simple or complex. Alternatively, you can scroll through the entire list of manuscripts, ordered chronologically. The result set will usually offer links to transcriptions and/or scans of manuscripts. For a pop-up display of metadata for each manuscript in the result set, click on "Metadata".
If you wish to match a term in "full text" mode, then type your query in the upper right-hand text box.