I believe the answers were written in a notebook, so there shouldn't be any writing in the materials themselves. However, I apologize if I missed anything. Regarding the 4-stage notebook, some parts were written in the booklet, but they have all been erased with an eraser. The practice problem collection has writing on the answer sheets (erased as much as possible). The answer sheets have been detached. The answer key has also been detached, but it is included. Please consider purchasing with the understanding that these are used items. No returns or refunds, please. I am also selling other reference books, so if you would like to purchase them as a set, please let me know in the comments section. #ReferenceBooks #UniversityEntranceExam