SKEW NAILING
There II be some situations where you cannot get at the end of the wood to use dovetail nailing. Here you must use skew nailing instead. This means glueing the two pieces securely together and then driving a nail into the upright piece of wood at an angle so it also penetrates the horizontal piece.
Put a couple of nails into each side of the upright so that they cross. To stop the upright moving, clamp a block of wood behind it or wedge it against something solid.