In the year before his premature death in 1999, Gian-Carlo Rota gave his famous course, Combinatorial Theory, at MIT for the last time. The late John N. Guidi (1954-2012) (audio) taped the lectures and took notes which he then wrote up in an almost verbatim manner conveying the substance and some of the atmosphere of the course. The Guidi Notes were available through MITÂ but only for a few years. Now this marvelous resource has become available on the Internet and can be downloaded here.