I bought this for my son who is taking entrance exams (to motivate him). Half of them are still in their original plastic packaging, unopened (;_;) * 10 books are unopened. * The first volume has some waviness on the back. * The other 11 books seem to have only been read once. * No folds. * No stains. They have been stored at home for a while, so the 11 opened books have some yellowing. I will sell them to someone who understands this. Returns are not accepted to prevent swapping.