Abstract: A gusset for assembling a first shelf and an identical transverse shelf in a corner arrangement without using a support column at the corner of the transverse shelf remote from the end edge of said first shelf. Said gusset comprises a lower portion having support surfaces abutting surface portions of a longitudinal rim flange of the first shelf and supports the lower surface of said shelf, and an upper portion having support surfaces abutting other surface portions of said longitudinal rim flange and resting on the upper surface of the shelf. When the upper and lower portions are clamped together by a screw the two assembled portions form recesses adapted to receive and clamp the free end of one of the longitudinal rim flanges of said transverse shelf.