Abstract: A book cover structure of the type having front and back covers for binding sheets therebetween. A backbone area is joined with the front and back covers. The backbone area is provided with spaced parallel strips of hot melt adhesive with transversely extending bridge means of hot melt adhesive extending therebetween the width of the backbone area. Spaced score lines are positioned between the parallel strips under the bridges in parallel relation relative to the strips to enable the user to flex the binding along selectable score lines relative to the backbone area. The bridge means of hot melt adhesive and the strips comprise means for holding sheets in bound engagement with the backbone area. The bridge means of hot melt adhesive extend across the score lines and thus provide continuity of adhesive on opposite sides of and across the score lines.

Abstract: An improved book cover structure of the general type having an integral backbone and front and back covers connected to the backbone via spaced parallel score lines to enable the front and back covers to flex relative to the backbone. A backbone strip of hot melt adhesive is secured on an inside face area of the backbone. Spacer means for positioning the outermost sheets in engagement with the backbone strip are provided and comprise cover strips of hot melt adhesive secured to inside surface areas of the front and back covers adjacent to the score lines with reduced area portions of the cover strips extending across the score lines.