Book cipher uses book's title, page number, row number and word number to make a secret message.
For example, code could look like this:
Adventures of Huckleberry Finn - 43 - 3 - 2, 43 - 5 - 14, 43 - 22 - 8. And we will get a clue - up in trees.
Also keep in mind that the same title book could be totally different. Different publishing house, different font, images, edit and so on. On computer or e-reader the page numbers could be totally different as well depending on the size of the screen. So if you are using this cipher then provide the actual book or PDF file from where the cipher originated.