Martin Kramer has been plagiarized.
For students: Since it's the beginning of an academic year, you might take a lesson from this episode, and spend an hour to learn what constitutes plagiarism. When I enrolled as a Princeton undergrad over thirty years ago, I received a copy of this booklet, which seems not to have changed since then. The definitions used at Princeton aren't some unobtainable gold standard. They're a minimal standard.
Good advice by the professor.