| 摘要 |
<p>A cover blank consisting of a single sheet having two cover panels hingedly connected to a central back panel by two hinge panels on opposite sides of the back panel, the panels having foldable flaps around their outside edges, the flaps being dimensioned and arranged so that, when folded to overlie the panels and one another, the cover panels have a two-, three- or four-layer thickness around their outside edges and a three- or four-layer thickness over most of their area, the back panel has a two-layer thickness around its outside edges and a one-layer thickness over most of its area, and the hinge panels have a two-layer thickness around their outside edges and a one- or two-layer thickness over most of their area.</p> |
