To eliminate wasteful use of envelopes for sending magazines or catalogs in large numbers by a method wherein an extension part having the same measure in the length as covers of a book is provided on the side of either one of the covers on which the book is opened and this extension part is bent onto the other cover and stuck on the upper or lower part thereof.

An extension part 3 having the same measure in the length as covers of a book is provided on the side of one cover 1 of the book being closed on which it is opened and the part is bent and stuck on the other cover 2. The measure of the extension part 3 is equal to the length of the covers of the book, while the width thereof is made equal to the dimension obtained by adding an extent to be used for a space of an invoice for sending, to the thickness of the pages of the book, for instance. The extension part 3 from one cover 1 of the closed book is bent onto the side on which the book is opened, and it is stuck on the other cover 2. On the occasion, an adhesive which loses the adhesion when the part is once peeled off. By using the top of the part for the space of the invoice for sending, it is made possible to dispense with an envelope for sending the book.