To facilitate a treatment for preventing reading while browsing at bookstore by providing adhesive surfaces on two sheet to be inserted into an arbitrary part of a book, providing a perforation longitudinally near edges of the sheet, folding a folding side of one sheet to the other sheet and adhering it.

Perforations 2a, 2b are respectively provided longitudinally near edges of rectangular sheets 1a, 1b. Double-sided tape is provided as an adhesive material on an adhesive surface 3 of the sheet 1a. Creases are longitudinally formed at folding sides (c) to (d) of the sheet 1b, and an adhesive surface 4 is folded. A mounting part 6 of the sheet 1a is coated with the adhesive material, and inserted fixedly into a gutter of a book 7. Them, a mounting part 5 of the sheet 1b is also coated with the material, and inserted fixedly into a gutter of other page. Thereafter, the sides (c) to (d) are folded, the surface 4 is fixed to the surface 3 of the sheet 1a for use. Thus, when the book 7 in which both the sheets 1a, 1b are mounted is to be read, the perforations 2a, 2b are cut open, and its contents are read.