Convection and cracking stability of spheres in general relativity Héctor Hernández, Luis A. Núñez and Adriana Vásquez-Ramírez Eur. Phys. J. C, 78 11 (2018) 883 Published online: 31 October 2018 DOI: 10.1140/epjc/s10052-018-6365-0