Shelf - MinecraftschurliMods/Bibliocraft-Legacy GitHub Wiki
Shelves can be used to store up to 4 items, which will be displayed in their corresponding slot. Only one item can be stored in a slot, even for stackable items. Shelves come in all wood types.
The shelf can be used in-world. Right-click with an item to add the item to the aimed-at slot, returning any item that may already have been present in that slot. Right-click with an empty hand to grab the item from the aimed-at slot. Right-click the wooden parts of the shelf, or with an empty hand on an empty slot, to open the GUI.