Shear-free condition and dynamical instability in f(R, T) gravity Ifra Noureen, M. Zubair, A. A. Bhatti and G. Abbas Eur. Phys. J. C, 75 7 (2015) 323 Published online: 11 July 2015 DOI: 10.1140/epjc/s10052-015-3547-x