Abstract: The invention relates to joint elements to support and secure shelves in bookcases or stands, and to a set of shelves employing said joint elements to secure the shelves in the uprights, comprising a first insertion part (1) designed to be inserted into a recess (10) directly obliquely downwards in the surface of the uprights (7, 8) and a bent section (2) connected to the insertion part (1), said bent section comprising a supporting portion (3) at the joining point between shelf and upright, directed substantially at right angles to the surface of the uprights and intended to support the shelf (6), and also a second insertion part (4), directed upwardly substantially at right angles to the supporting portion (3) and intended to be inserted in a recess (9) arranged substantially perpendicularly in the lower surface of the shelf.