I found this
Review.
I'm very suspicious of note-books. This is because everyone knows that when you draw in a note-book you usually leave some kind of impression, even if it's only a faint one on the next page. Anyone guessing how the effect was achieved would suggest that you somehow saw this impression when you took back the book.
I saw S. Lea's notepad in action shortly after christmas and what I liked about that was that the notebook doesn't need to be reopened so even if the spec leaves a natural impression there's no way anyone could have seen it. If I remember correctly, he puts the notebook straight into his pocket and doesn't bring it out again after the effect.