The ` crossing ' or exchanging of books may take many different forms , including wild releasing books in public , direct swaps with other members of the website , or `` book rings '' in which books travel in a set order to people who want to read that book . The ` crossing ' or exchanging of books may take any of a number of forms , including wild releasing books in public , direct swaps with other members of the websites , or `` book rings '' in which books travel in a set order to participants who want to read a certain book .