As a rule, whenever I remove stickers from books (my other hobby), I tend to use lighter fuel first. It's very volatile so evaporates the quickest and although smelly in use leaves zero trace when it dries off even on the most delicate of paper or plastic. It only works with some adhesives so my next step up is 99% IPA. That can loosen paint or ink if you rub too hard so you need to be careful. After that, I go for the proprietary label removers. There are a few. They should be OK on hard plastics but can leave a permanent stain on paper. You will just have to try one after the other until one works. Most use some form of limonene, which is toxic, so best handled with gloves and in a well aired area. The last resort is heat. Safer on paper and card but quite a risk with plastics to lift a well adhered sticker.
Never, ever go near acetone or nail polish remover. Quite effective on glue but even more so on breaking down plastics. It will scar your iBook. Goo Gone doesn't sell in my country so I can't advise on that particularly. I would just use IPA or rubbing alcohol if you have some. It's pretty effective on even dried and hardened glue residue once the paper is gone.
Never, ever go near acetone or nail polish remover. Quite effective on glue but even more so on breaking down plastics. It will scar your iBook. Goo Gone doesn't sell in my country so I can't advise on that particularly. I would just use IPA or rubbing alcohol if you have some. It's pretty effective on even dried and hardened glue residue once the paper is gone.