I borrowed a math book from a library. And my 5-year-old cousin decides to put some Dragon Ball Z sticker on a few pages of the book. The stickers seem to be very strong. how can I remove the stickers without ruining the pages and making sure that I don't leave a bad stain?
Try with a cotton bud engaged with hot water, rub it up (gently) against the borders, the sticker shuold unplug. Be sure the water isn't too much (it could erode the paper cover). If the water doesn't work or if after the procedure there is still some glue take another cotton bud engaged with nail polish remover and pass it on the glue. I've worked in book restoration and this procedure worked pretty well even with scotch tape and old glue stains on paper.
Experiment using another sticker and similar paper before you try anything on the book. I suggest you try freezing the book and removing the sticker while it’s cold. Be careful of condensation forming when you take the book out of the freezer, though. Best if you can do it in a low humidity environment.