I got this tip from our real-estate agent. Here’s how to deodorize old books.
Place the book in an airtight container. Fill the container with either baking soda or cat litter. Leave the book/s and filler in the container for a few days.
A book’s musty smell is generally caused dampness, which could produce mold. If the book you want to restore is damp, dry it out before deodorizing. Place the book upright on a table with the pages fanned out. Use a fan to accelerate the process.