Philip T. Barton Dimitris Drikakis Evgeniy Romenski V. A. Titarev Exact and approximate solutions of Riemann problems in non-linear elasticity. 7046-7068 2009 228 J. Comput. Physics 18 http://dx.doi.org/10.1016/j.jcp.2009.06.014 db/journals/jcphy/jcphy228.html#BartonDRT09