fem elasticity

I'm very interested in the choice of the finite element spaces for elasticity. I want to choose elements for the stress and the velocity, I was suggested to use piecewise constant for the stress and piecewise linear for the velocities to satisfy the Babuska-Brezzi condition. Is that right? I've heard that I can't use only 6 components for the stress in this way, but I must add some additional constraint to enforce its simmetry. I'm looking for additional documentation, but I can't find any. Has someone got any suggestion? Thanks.