@article{CRMATH_2003__337_4_233_0,
     author = {Sergio Conti and Camillo De~Lellis and Stefan M\"uller and Mario Romeo},
     title = {Polyconvexity equals rank-one convexity for connected isotropic sets in $ \mathbb{M}^{\mathrm{2\times 2}}$},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {233--238},
     publisher = {Elsevier},
     volume = {337},
     number = {4},
     year = {2003},
     doi = {10.1016/S1631-073X(03)00333-9},
     language = {en},
}