| 摘要 |
PROBLEM TO BE SOLVED: To provide a cover having a through hole for engaging a rivet and a pair of cutouts or slits formed at dial positions of the through hole at a rivet receiving hole in the cover having the rivet receiving hole for mounting a binder. SOLUTION: The cover 1 is made of a relatively hard and thick synthetic resin such as a polypropylene or a cardboard, and bent to form a front cover 2, a rectangular backbone 3 and a rear cover 4. At least two rivet receiving holes 5 each having a diameter slightly larger than a diameter of a rivet are formed through the backbone 3 along a centerline of its longitudinal direction. Slender cutouts 6 are formed through both sides of the each hole 5 in a direction crossing the center.
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