Today most of the people by habit associate the book mainly with reading. History, however, proves that in practice the book can be used for everything. A recent example is this Harry Potter specimen with a concealed compartment in it. I found it 4-5 years ago next to a garbage container in Sofia, Bulgaria. According to my students' proposal it was used for hiding of marijuana. Till now I have seen such books only in westerns - with secret pistol or a TNT inside. Can you share similar examples?