Plumber: Most of the odor has probably been absorbed only by the exposed surfaces, and over an extended period, exposure of those surfaces to fresh air in a room with good circulation should cause the smell to fade. Depending on the value of the book, I would also consider lightly wiping the cover and the edges of the paper with Febreeze, but not on something rare (at least without first experimenting on something that was similar, but not so rare or valuable). I also found a description of a more serious approach out on the Web ... it sounds reasonable, but you'll need to judge its value for yourself (see below). Good luck. TT
P.S. -- What's the title you're trying to restore?
"I'd recommend putting the book into a chamber of some sort (I use a large rigid plastic box with a sealable lid) together with a zeolite, such as activated charcoal. I've experimented with several books that smelled musty by wrapping them well in pellon (spun polyester material, sold in fabric stores), then burying the wrapped book in deodorizing cat litter, which has a zeolite in it. After a few days the books smell fine, but as they weren't MY books, I don't know whether they have remained odor free. However, no one has told me the smell came back."