I had a book of mazes as a kid that had a dark brown cover. It was a pretty thin book. The mazes were very dense. It was very easy to cross over a line and get lost. The mazes had titles and that’s it. It looked like a research journal. There’s no way I could find it now.
A few images of insanely dense blank ink mazes. (More: The Seven Year Maze.)
Papers and images related to a algorithm for generating mazes as a type of ‘non-photorealistic rendering’.