This is one of my absolutely favorite Seinfeld episodes. It's pitch perfect, with Phillip Baker Hall playing library cop Bookman. I love it. I love every minute of it.
Jerry checked out a book in 1971 from the library and is in trouble with the library cop, George runs into an old high school teacher and Kramer dates the librarian. It's all perfect. One of the best episodes of the series and the third season, along with "The Parking Garage", "The Tape", "The Pen", "The Red Dot", and "The Boyfriend".
Hats off to a great third season.