Things change, especially in libraries. Books that were acquired in 1963 for the general collections have matured into rare books. The gorgeous publisher's cloth bindings, the scarcity of these titles in their original cover and their significance as milestones in their subject area are all factors in the transition to special collections.
Which means it is time to get the barcode stickers off the front cover. It can be done, but not all stickers stick the same. You've got to be ready for things to go smoothly like the two dark green books that had the same type of sticker, (the plastic carrier lifted nicely as did the residual adhesive when I applied a vinyl eraser) or not so smoothly as with the other book that had a different type of sticker (the paper carrier lifted quite readily, but the residual adhesive did not agree with the vinyl eraser). You've got to be ready to adapt your original plan, have another type of eraser on hand, or maybe a scalpel with a curved blade, not the straight blade. And if that doesn't work then be ready to try the hot air pencil, (maybe rolling the adhesive off with a metal spatula or maybe with an eraser) all the while paying close attention to the cloth of the book to make sure you are just lifting the sticker and residual adhesive and not scuffing the cloth or decoration and making a bigger mess.
And try not to cut yourself with the scalpel.