Hi Stefanel1 here in the U.S. we have only a few places to get stickers one is international auto parts www.interational-auto.com another is AR-Ricambi.
International auto parts has a sticker I think you might like it has a Quadrifoglio and say "alfa corse" it is about 6 cm in size. I do not know if they ship over seas. I would be more than happy to help you with shipping and finding stickers you like.
alfa-chan just had a thead on alfabb [this site] called "bad luck" about stickers it is in the gtv section you may want to look at that.
Do not worry about your English it is much better than my French.