Well, that's awesome artwork.....I don't think these are likely books that are being read anymore....it sounds like, and I'm just guessing here, that they are books that would likely go into recycle if this use wasn't given them. I think it's beautiful that these likely outdated documents have got a permanent place in the world of art rather than meeting the meltdown master of all paper that becomes irrelelvant or useless for our everyday needs. Really nice works....my guess for the pages stuck together would be either glue or a lot of pressure. Paper under pressure behaves a lot like wood. Go figure, it's basically a wood product with a whole bunch of chemicals added.