I am trying to track down a copy of Graeme Segal's 1999 lecture notes on topological field theory. These are sometimes referred to as the "Stanford lectures" or something similar.
For many years these unpublished notes were available at Duke's mathematics website via the link: http://www.cgtp.duke.edu/ITP99/segal/
However this link is now dead. Every reference I have found by googling seems to lead back to this dead link. It would be a tragedy if these lecture notes were lost to the mathematics community. I am hoping that somebody out there has retained a copy.