Find an appropriately sized hardback cover to replace the paperback cover. Remove the soft cover with a utility knife, scraping carefully along the spine to prevent the pages from separating.
Sand the spine gently to expose paper fibers. This will help the glue adhere better to the pages along the spine.
Clamp the pages together at either end of the book using the binder clips. The spine should remain completely exposed.
Spread a thin layer of glue along the entire spine. You can use just about any kind of glue, although super glue will probably give you the best results. Let the glue dry.
Apply another thin layer of glue to the spine of the new cover and press it to the pages. Use books or other heavy items to apply pressure to the spine and cover of the book. Let the glue dry.