Method:
Simply locate the purple-jacketed books and click on them. Make sure you do this as soon as you can, as some can't be gone back to! This is ESPECIALLY important for the one on Terror Island.
Inside the Locksmith's store, on the windowsill
Inside the Governor's Mansion, on the rear bookshelf
Inside the Fish Shop, beneath the flag by the door
In Toothrot's cave on Terror Island, at the bottom of the screen (Pick this up AS SOON as you enter, or you may lose it forever!)
Inside the Queen's Ice Palace on Brrr Muda, by the Queen's two guards